MODAL AUXILIARIES

General characteristics of modal verbs

Which verbs are modal auxiliaries and what they do?

Verbs like can and may are called modal auxiliaries, though we often refer to them simply as modal verbs or modals. We frequently use modals when we are concerned with our relationship with someone else. We may, for example, ask for permission to do something; grant permission to someone; give or receive advice; make or respond to requests and offers, etc. We can express different levels of politeness both by the forms we choose and the way we say things.

Modals sharing the same grammatical characteristics are:

can could

may might

will would

shall should

must

ought to

Verbs which share some of the grammatical characteristics of modals are: need, dare, used to.

By comparison, need to and dare to are full verbs.

Modals have two major functions which can be defined as primary and secondary.

Primary function of modal verbs

In their primary function, modal verbs closely reflect the meanings often given first in most dictionaries, so that:

can/could relate mainly to ability: I can lift 25 kg./I can type.

may/might relate mainly to permission: You may leave early.

will/would relate mainly to prediction: It will rain soon.

shall after I/we relates mainly to prediction: Can we find our way home? Im sure we shall.

should/ought to relate mainly to escapable obligation or duty: You should do (or ought to do) as youre told.

must relates mainly to inescapable obligation: You must be quiet.

neednt relates to absence of obligation: You neednt wait.

Secondary function of modal verbs

In their secondary function, nine of the modal auxiliaries (not shall) can be used to express the degree of certainty/uncertainty a speaker feels about a possibility. They can be arranged on a scale from the greatest uncertainty (might) to the greatest certainty (must). The order of modals between might and must is not fixed absolutely. It varies according to situation. For example, one arrangement might be:

Some ways in which modals resemble be, have, do

Structurally, modal auxiliaries resemble the auxiliaries be, have and do in some ways and differ completely from them in others. Some of the most important similarities are noted in this section and some differences are explained in section 5.

The negative

The negative is formed (as it is for be, have and do) by the addition of not after the modal. In informal spoken English not is often reduced to the unemphatic nt:

be (is) not (is)nt

have (have) not (have)nt

do (do) not (do)nt

can cannot cant

could could not couldnt

may may not -

might might not mightnt

will will not wont

would would not wouldnt

shall shall not shant

should should not shouldnt

must must not mustnt

ought to ought not to oughtnt to

need need not neednt

dare dare not darent

Questions

Yes/No questions are formed as for be, have and do. We begin with the modal, followed by the subject and then the main verb:

May we leave early?

In question-word questions, the question-word precedes the modal:

When may we leave?

With Yes/No questions, the modal used in the answer is normally the same as the one used in the question:

Can you come and see me tomorrow? Yes, I can./No, I cant.

Modals also behave like be, have and do in tag questions:

You can do it, cant you?

Negative questions

As with be, have and do, the full form of negative questions with modals requires not after the subject (Can you not help me?). This is formal and rare. Contracted forms are normally used:

Cant you help me?

Some ways in which modals differ from be, have, do

Defective verbs

Modals are sometimes called defective verbs because they lack forms ordinary full verbs have. For example:

Modals cannot be used as infinitives (compare to be, to have, to do). If ever we need an infinitive, we have to use another verb:

If you want to apply for this job, you have to be able to type at least 60 words a minute. (Not *to before can or can alone)

We do not use a to-infinitive after modals (compare be to, have to). Only the bare infinitive can be used after modals (except ought, which is always followed by to):

You must/mustnt phone him this evening. (Not *to phone)

Modals have no ing form (compare being, having, doing). Instead of ing, we have to use another verb or verb-phrase:

I couldnt go/I wasnt able to go home by bus, so I took a taxi. (=Not being able to go home by bus, I took a taxi.)

Modals have no (e)s in the 3^rd person singular (compare is, has, does):

The boss/He can see you now. (No s on the end of can)

Each modal has a basic meaning of its own. By comparison, as auxiliaries, be/have/do have only a grammatical function.

One modal at a time

Only one modal can be used in a single verb phrase:

We may call the doctor.

We must call the doctor.

But not may and must together.

If we wish to combine the two ideas in the above sentences, we have to find a suitable paraphrase:

It may be necessary (for us) to call a doctor.

By comparison, we can use e.g. be and have together:

It has been necessary to call a doctor.

Forms and uses of modals compared with verb tenses

The labels we use to describe the verb tenses (e.g. present, progressive, past, perfect) cannot easily be applied to modals.

Present

All modals can refer to the immediate present or the future, therefore present is not always a reliable label:

I can/may (etc.) phone now. I can/may (etc.) phone tomorrow.

Progressive

There is no progressive form for modals. But we can put the verb that follows a modal into the progressive form:

Meg is phoning her fianc (present progressive)

Meg may be phoning her fianc. (modal + be + verb-ing)

Meg may have been phoning her fianc. (modal + have been + -ing)

It is the phoning that is or was in progress, not may.

Past

Would, could, might and should can be said to be past in form, but this usually has little to do with their use and meaning. They can be called past when used in indirect speech:

He says you can/will/may leave early. (present)

He said you could/would/might leave early (past)

Might can have a past reference in historical narrative:

In the 14^th century a peasant might have the right to graze pigs on common land.

However, might usually expresses more uncertainty than may:

I might see you tomorrow.

is less certain than:

I may see you tomorrow.

Could sometimes expresses ability in the past:

He could (or was able to) swim five miles when he was a boy.

but could is not possible in:

I managed to/was able to finish the job yesterday.

However, couldnt and wasnt able to are usually interchangeable:

I couldnt/wasnt able to finish the job yesterday.

The other main use of could, as a more polite alternative to can in requests, has nothing to do with time:

Could you help me please?

Would expresses the past in:

When we were young we would spend our holidays in Brighton.

Otherwise, would and should have special uses.

Must can express past time only in indirect speech; otherwise it has to be replaced by have to:

He told us we must wait (or we had to wait) until we were called.

She asked her boss if she must work (or had to work) overtime.

Perfect and past

Forms with modal + have + past participle or with modal + have been + progressive are not necessarily the equivalent of the present perfect. The modal refers to the present, while have + past participle refers to the past. So, depending on context,

You must have seen him can mean:

I assume (now) you have seen him. (i.e. before now; equivalent to the present perfect)

I assume (now) you saw him. (i.e. then; equivalent to the past)

I assume (now) you had seen him. (i.e. before then; equivalent to the past perfect)

Modal + be/have been + progressive

Two observations need to be made here:

Modal + be/have been + progressive is not always possible in the primary function. For example:

He cant leave yet. (= its not possible for him to leave yet)

is quite different from the secondary function:

He cant be leaving yet. (= I dont think he is)

But compare the primary and secondary functions of must in:

Primary:  You must be working when the inspector comes in. (i.e. it is necessary (for you) to be working.)

Secondary:  You must be joking! (i.e. Im almost certain you are joking.)

Occasionally, in the primary function, a modal + be + progressive has a softening effect similar to the use of the future progressive. So:

We must/may/should (etc.) be leaving soon.

is more polite than:

We must/may/should (etc.) leave soon.

Uses of modals to express ability

Can = ability: the present

Can + verb (natural ability)

Natural ability can be expressed as follows:

Can you run 1500 metres in 5 minutes? (=Are you able to run? Are you capable of running?)

Can and be able to are generally interchangeable to describe natural ability, though able to is less common:

Bill is only 9 months old and he can already stand up.

Bill is only 9 months old and he is already able to stand up.

However, be able to would be unusual when we are commenting on something that is happening at the time of speaking:

Look! I can stand on my hands!

Can + verb (learned ability or know-how

Learned ability can be expressed as follows:

Can you drive a car? (= Do you know how to? Have you learnt how to?)

I can/cannot/cant drive a car.

Verbs such as drive, play, speak, understand indicate skills or learned abilities. Can, and to a lesser extent, be able to, often combine with such verbs and may generally be used in the same way as the simple present tense:

I can/cant play chess. (= I play/dont play chess.)

Could/couldnt = ability: the past

Past ability (natural and learned) expressed with could

Could, couldnt or was/were (not) able to can describe natural and learned ability in the past, not related to any specific event:

Jim could/couldnt run very fast when he was a boy.

Barbara could/couldnt sing very well when she was younger.

Jim was able to/was unable to run fast when he was a boy.

We also often use used to be able to to describe past abilities:

I used to be able to hold my breath for one minute under water.

Could and was (or would be) able to occur after reporting verbs:

He said he could see me next week.

The past: could + verb: achievement after effort

Could and was/were able to can be interchangeable when we refer to the acquisition of a skill after effort:

I tried again and found I could swim/was able to swim.

Specific achievement in the past

Could cannot normally be used when we are describing the successful completion of a specific action; was/were able to, managed to or succeeded in + -ing must be used instead:

In the end they were able to rescue/managed to rescue/succeeded in rescuing the cat on the roof.

If an action was not successfully completed, we may use couldnt:

They tried for hours, but they couldnt rescue the cat. (or werent able to, didnt manage to, etc.)

Could can be used when we are asking about a specific action (as opposed to describing it):

Could they rescue the cat on the roof? (= did they manage to?)

-No, they couldnt. It was too difficult.

However, an affirmative response requires an alternative to could:

-Yes, they managed to. (Not *could)

Can/could + verbs of perception

Verbs of perception like see, hear, smell, rarely occur in the progressive. Can, and to a lesser extent, be able to, combine with such verbs to indicate that we can see, hear, etc. something happening at the moment of speaking. In such cases can has a grammatical function equivalent to the simple present in statements and to do/does in questions and negatives:

I can smell something burning. (= I smell something burning.)

I cant see anyone. (= I dont see anyone.)

Could can be used in place of the simple past in the same way:

I listened carefully, but couldnt hear anything. (= I listened carefully, but didnt hear anything.)

Can/could can be used with verbs suggesting understanding:

I can/cant understand why he decided to retire at 50.

I could/couldnt understand why he had decided to retire at 50.

Cant/couldnt cannot be replaced by the simple present or simple past when conveying the idea beyond (my) control (impossible):

I cant (couldnt) imagine what it would be like to live in a hot climate. (Not *I dont/didnt imagine)

Ability in tenses other than present and past

If we need to express ability in other tense combinations (e.g. the future or the present perfect), then the appropriate forms of be able to, manage to or succeed in must be used:

Ill be able to pass my driving test after Ive had a few lessons.

Ive been trying to contact him, but I havent managed to.

Can, referring to ability, skill, or perception, is usable in clauses after if and when to refer to the future:

If you can pass (or are able to pass) your driving test at the first attempt, Ill be very surprised.

Can/could = capability/possibility

Can + be + adjective or noun has the effect of is sometimes or is often and refers to capability or possibility. It can be replaced by be capable of + -ing, but not be able to:

It can be quite cold in Cairo in January. (= It is sometimes or often quite cold.)

He can be very naughty. (or a very naughty boy)

(When used for people, the effect is generally negative, even when the adjective is favourable: She can look quite attractive when she wants to which implies she doesnt usually look attractive.)

Could has the same effect in the past:

It could be quite cold in Cairo in January when I lived there. (= It was sometimes or often quite cold.)

Could can also have a future reference in this kind of context:

It could be quite cold when you get to Cairo.

Uses of modals to express permission and prohibition

Asking for permission/responding: can/could/may/might

Requests for permission can be graded on a hesitancy scale, ranging from a blunt request to an extremely hesitant one. Requests for permission can refer to the present or future. The basic forms are:

Can

Could

May

Might

Can is the commonest and most informal:

Can I borrow your umbrella (please)?

A few (old-fashioned) native speakers still hold that can is the equivalent of be able to and therefore may must be used instead. The idea of e.g. asking for a favour is less strong in can than in could/may/might.

Could is more hesitant and polite than can. We often use it when we are not sure permission will be granted:

Could I borrow your umbrella (please)?

May is more formal, polite and respectful than can and could:

May I borrow your umbrella (please)?

Might is the most hesitant, polite and respectful and is rather less common than the other three:

Might I borrow your umbrella (please)?

In practice, can, could and may are often interchangeable in neutral requests.

Common responses with modals are: e.g.

- affirmative: Of course you can/may. (Not *could/might)

- negative: No, you cant/may not. (Not *could not/might not)

Numerous non-modal responses are possible, ranging from the polite Of course (affirmative), Im afraid not, Id rather you didnt (negative) to blunt refusal like Certainly not. A polite refusal is usually accompanied by some kind of explanation (Im afraid you cant because).

Permission to ask an indiscreet question may be requested with the formulas if I may ask and (more tentative) if I might ask:

How much did you pay for this house if I may/might ask?

Granting and refusing permission

Permission can be granted or refused as follows:

You can(not)/may (not) watch TV as long as you like.

You may/may not carries the authority of the speaker and is the equivalent of I (personally) give you permission. You can/cannot is more general and does not necessarily imply personal permission. Permission issuing from some other authority can be granted or withheld more emphatically with be allowed to, be permitted to, and be forbidden to, as follows:

You can/cannot or Youre allowed/not allowed to

You can/cannot or Youre permitted/not permitted to

You mustnt or Youre forbidden to

Granting/refusing permission is not confined to 1^st and 2^nd persons:

John can/may/cant/may not/mustnt stay up late.

This can be extended to:

rule-making e.g. for games: Each player may choose five cards.

other contexts: Candidates may not attempt more than three questions.

Permission may also be given by a speaker with shall in the 2^nd and 3^rd persons (formal and literary):

You shall do as you please. (i.e. you have my permission to)

He shall do as he pleases. (i.e. he has my permission to)

Permission may also be denied with shant in British English only:

If you dont behave yourself, you shant go out.

If he doesnt behave himself, he shant go out.

Numerous alternative forms are available to express anything from mild refusal (Id rather you didnt if you dont mind) to strong prohibition (I forbid you to). Formal and strong statements with non-modal forms are often found in public notices:

Thank you for not smoking. (i.e. please dont)

Passengers are requested to remain seated till the aircraft stops.

Trespassing is strictly forbidden.

Permission/prohibition in other tenses

The gaps in the defective verbs may and must can be filled with the verb phrases be allowed to and the more formal be permitted to. Examples of other tenses:

present perfect: Mrs James is in hospital and hasnt been allowed to have any visitiors.

past We were allowed to stay up till 11 last night.

Could can only express past permission in general:

When we were children we could watch (or were allowed to watch) TV whenever we wanted to.

Uses of modals to express certainty and possibility

Certainty, possibility and deduction

If we are certain of our facts, we can make statements with be or any other full verb:

Jane is (or works) at home. (a certain fact)

If we are referring to possibility, we can use combinations of may, might or could + verb:

Jane may/might/could be (or work) at home. (a possibility)

We may draw a distinction between the expression of possibility in this way (which allows for speculation and guessing) and deduction based on evidence. Deduction, often expressed with must (affirmative) and cant (negative), suggests near-certainty:

Janes light is on. She must be at home. She cant be out.

Forms of tenses (certainty) versus modals (possibility)

certain possible/less than certain

(expressed by verb tenses)  (expressed by may, might and could)

He is at home. He may/might/could be at home (now).

He will be at home tomorrow. He may/might/could be at home tomorrow.

He was at home yesterday.  He may/might/could have been at home yesterday.

He leaves at 9. He may/might/could leave at 9.

He will leave tomorrow.  He may/might/could leave tomorrow.

He has left. He may/might/could have left.

He left last night.  He may/might/could have left last night.

He will have left by 9. He may/might/could have left by 9.

He is working today. He may/might/could be working today.

He will be working today.  He may/might/could be working today.

He was working today. He may/might/could have been working today.

He has been working all day.  He may/might/could have been working all day.

He will have been working all day.  He may/might/could have been working all day.

Notes on modal forms expressing possibility

Should be and ought to be to express possibility

In addition to the above examples, we can also express possibility with should be and ought to be:

John should be/ought to be at home.

John should be/ought to be working.

John should have left/ought to have left by tomorrow.

However, because should and ought to also express obligation, they can be ambiguous, so are not used as much as may/might/could to express possibility. For example, He should have arrived (ought to have arrived) yesterday could mean I think he probably has arrived or He failed in his duty to arrive yesterday.

Questions about possibility

When we are asking about possibility, we may use Might?, Could? and sometimes Can? and (rarely) May?. (We do not normally use should and ought to in affirmative questions about possibility because of the risk of confusion with obligation):

Might/could/can this be true?

Might/could he know the answer?

Might/could/can he still be working? (or be still working)

Might/could he be leaving soon?

Might/could/can he have been waiting long?

Might/could he have left by tomorrow?

Can is not always possible in questions like these, probably because of the risk of confusion with can = ability. However, in questions like Can this be true?, can often indicates disbelief. Can is possible in some indirect questions:

I wonder where he can have left the key?

Negative questions about possibility

Negative questions about possibility can be asked with Mightnt and Couldnt, May not can sometimes be used, as can Shouldnt and Oughtnt to:

Mightnt he be at home now?

Couldnt he know the answer?

Negative possibility

Negative possibility is expressed with may not, mightnt, cant and couldnt, but not usually with shouldnt and oughtnt to:

He may not be (or have been) here.

He may not be (or have been) working late.

Cant + be often suggests disbelief:

What youre saying cant be true! I can hardly belief it!

Can may be used in negative indirect questions:

I dont think he can have left home yet.

Or in semi-negatives: He can hardly be at home yet. Its only 6.

Modals on a scale of certainty

Degrees of certainty can be expressed on a scale:

He is at home. (= its a certain fact: non-modal be)

He could be at home. (=doubtful possibility)

He should be at home. (= doubtful possibility)

He ought to be at home. (= doubtful possibility)

He may be at home. (= its possible, but uncertain)

He might be at home. (= less certain than may)

He isnt at home. (= its a certain fact )

He cant be at home. (= its nearly certain)

He couldnt be at home. ( = more tentative than cant)

He may not be at home. (= possible, but uncertain)

He mightnt be at home. (= less certain than may not)

In speech, the element of doubt is increased with heavy stress:

He `could be at home. (i.e. but I very much doubt it)

Particular stress is also used in exclamations:

It `cant be true! You `cant mean it! You `must be mistaken!

Certain and uncertain responses to questions

Yes/No answers to questions can reflect varying degrees of certainty felt by the speaker. For example, a certain question may elicit an uncertain answer:

Does he like ice-cream? (direct question)

- Yes, he does./No, he doesnt (certain answer)

- He might (do). He may (do). He could (do). (possibility)

- He mightnt. He may not. (uncertainty)

Similarly, an uncertain question may elicit a certain answer:

Can he still be working? (disbelief)

Mightnt he be working? (possibility)

- Yes, he is./No, he isnt. (certain response)

- He might (be). He may (be). (possibility)

- He may not be. I dont think he can be (possibility)

- He cant be. He couldnt be. (disbelief)

Of course, any other answer, not necessarily involving the use of a modal verb, may be available, depending on circumstances:

- I dont know. Im not sure. I dont think so, etc.

Be and have been are normally used in answers to questions with be:

Is he ill? He may be.

Was he ill? He may have been.

Do often replaces other verbs:

Will you catch an early train? I may do.

Has he received my message? He could have/could have done.

Uses of modals to express deduction

Examples of modal forms for deduction

must and cant

present reference:

Certainty expressed by verb tenses:

He is here. He lives here. He is leaving.

He isnt here. He doesnt live here. He isnt leaving.

Deduction expressed by must and cant:

He must be here. He must live here. He must be leaving.

He cant be here. He cant live here. He cant be leaving.

perfect and past reference:

Certainty expressed by verb tenses:

He was here. He has left./He left early. He has been/was working late.

Deduction expressed by must + have + past participle and cant/couldnt + have + past participle:

He must have been here. He must have left early. He must have been working late.

He cant have been here.  He cant have left early. He cant have been working late.

He couldnt have been here. He couldnt have left early. He couldnt have been working late.

Expressing deduction with must and cant

The distinction between possibility (often based on speculation) and deduction (based on evidence) has already been drawn. The strongest and commonest forms to express deduction are must and cant. For teaching and learning purposes, it is necessary to establish the following clearly:

cant (not *mustnt) is the negative of must

cant have + 3^rd form (not *must have + 3^rd form) is the negative of must have + 3^rd form

Have to/have got to (affirmative) can express deduction in AmE:

This has to be/has got to be the most stupid film I have ever seen.

Compare deduction (secondary use of modals) in:

He cant be thirsty.  He must be hungry.

He cant have been thirsty.  He must have been hungry.

with inescapable obligation (primary use of modals) in:

He mustnt be careless.  He must be careful.

He didnt have to be at the dentists. He had to be at the doctors.

We also use may/might/could and should/ought to for making deductions (as well as for expressing possibility); and, when we are almost certain of our evidence, we may use will and wont:

This will be Roland. I can hear him at the door.

That will have been Roland. He said hed be back at 7.

That wont be Roland. Im not expecting him yet.

That wont have been Roland. Im not expecting him till 7.

Again, it is possible to give varying responses to a question:

Is Roland in his room?

- Yes, he is./No, he isnt.  (certainty)

- Yes, he must be. I heard him come in. (deduction)

- No, he wont be. He had to go out.  (near-certainty)

- No, he cant be. Theres no light in his room. (deduction)

Uses of modals for offers, requests, suggestions

General information about offers, requests and suggestions

Modal verbs are used extensively for language acts or functions such as offering, asking for things, expressing preferences. Fine shades of meaning are conveyed not only by the words themselves, but particularly by stress, intonation, and gesture. (Note that we can also make suggestions, etc. with non-modal forms, e.g. Have a drink., Lets go to the zoo.). In this section, offers, requests, etc. are considered from six points of view under two headings:

Things and substances

Offering things and substances + appropriate responses

Requests for things and substances + appropriate responses

Actions

Making suggestions, inviting actions + appropriate responses

Requesting others to do things for you + appropriate responses

Offering to do things for others + appropriate responses

Suggestions that include the speaker.

Things and substances: offers with modals

Typical offers inviting Yes/No responses

Can/Could I offer you a sandwich/some coffee?

Will/Wont you have a sandwich/some coffee?

Would/Wouldnt you like a sandwich/some coffee?

Typical responses

There are many non-modal forms (Yes please, No thank you, etc.) and a few modal ones:

Yes, Id like one/some please. Yes, Id love one/some please.

However, we dont usually repeat the modal when we refuse an offer. A reply like No, I wont in answer to Will you have? could sound rude.

Typical offers with What

What will you have? What would you like to have?

What would you prefer? What would you rather have?

Things and substances: requests with modals

Typical requests inviting Yes/No responses

Can/Could/May/Might I have a sandwich/some coffee (please)?

Typical responses

Of course you can/may. (not *could/might)

No, you cant/may not (Im afraid).

These answers with modals would be likely where e.g. a parent is addressing a child. Adult responses would be e.g. Certainly or Im afraid there isnt any, etc.

Actions: suggestions/invitations with modals

Typical suggestions inviting Yes/No responses

Will you/Wont you come for a walk (with me)?

Would you/wouldnt you like to come for a walk (with me)?

Typical responses

(Yes.) Id like to. Id love to.

(No.) Id prefer not to, thank you.

Typical inquiry with What to invite suggestions

What would you like to do?

Actions: using modals to ask someone to do something

Typical requests inviting Yes/No responses

Will you?, Would you? in these requests refer to willingness. Can you?, Could you? refer to ability.

Will you (please) open the window (for me)?

Can/Could you (please) open the window (for me)?

Would you (please) open the window (for me)?

Would you like to open the window (for me)?

Would you mind opening the window (for me)?

Will/Would you sounds even more polite with the addition of kindly and can/could with the addition of possibly:

Will/Would you kindly? Can/Could you possibly?

We cannot use May you? in requests for help.

Typical responses

Yes, of course (I will). No, Im afraid I cant (at the moment).

Actions: using modals to offer to do things for others

Typical offers to do things

Offers beginning Shall I ?, Shall we ? are very common:

Can I/Could I/Shall I open the window (for you)?

Would you like me to open the window (for you)?

Thats the phone. Ill get it for you, (shall I)?

What shall/can I do for you?

And note very polite offers with may in e.g.:

May I take your coat?

Typical responses

The usual responses are Yes please, No thank you, or tag responses like Can/Could/Would you? Thats very kind, but not Yes, you can/No, you cant, which could sound rude.

Actions: suggestions that include the speaker

Typical suggestions inviting Yes/No responses

Shall we go for a swim? We can/could/might go for a swim.

Typical responses

Yes, lets, (shall we)?

No, Id rather we didnt./No, Id rather not.

Typical inquiries with What

What shall/can/could we do this afternoon?

Advisability, duty/obligation and necessity

Examples of forms expressing advisability, etc.

present advisability past advisability not acted upon

I should stop smoking. I should have stopped smoking.

I ought to stop smoking.  I ought to have stopped smoking.

Id better stop smoking (I was advised to stop but

(I still smoke.) ignored the advice.)

present inescapable obligation   past inescapable obligation

I must stop smoking. I had to stop smoking.

(I am obliged to stop smoking  (I was obliged to stop smoking

and I shall: it is my duty.) and I did: it was my duty.)

Advisability necessity: a scale of choice

We can use modals and other verbs to express advisability on a scale which reflects a degree of choice. This scale may vary according to the subjective point of view of the speaker.

advisability should: generally means in my opinion, it is advisable to or it is

(your) duty.

ought to: can be slightly stronger than should in that it is sometimes

used to refer to regulations or duties imposed from the

outside: You ought to vote (= it is your public duty).

Should is more likely than ought to in questions and

negatives.

had better: is stronger than should and ought to. It is used to

recommend future action on a particular occasion, not in

general. It carries a hint of threat, warning or urgency:

Youd better see a doctor.

be to: can be used for instructions:

Youre to report for duty at 7.

need (to): (= it is necessary to).

have to: is an alternative to must and fills the gaps in that defective

verb.

have got to: like have to, but more informal.

necessity must: like have to and have got to, suggests inescapable

obligation. In the speakers opinion there is no choice at all.

Must, have to and have got to

As far as meaning is concerned, these three forms are largely interchangeable. However, there are differences between them. When used in the 1^st person, have to and have got to can refer to an external authority and might be preferable to must in: e.g.

We have to/Weve got to send these VAT forms back before the end of the month. (i.e. we are required to do so by law)

On the other hand, must can express a speakers authority over himself and might be preferable to have to/have got to in:

I/We really must do something about the weeds in this garden. (i.e. but I dont have to account to anybody if I dont)

In other persons (you, etc.) must always conveys more strongly than have to the idea of inescapable obligation or urgency in: e.g.

You must phone home at once. Its urgent.

Have to and have got to are interchangeable for single actions:

I have to/have got to check the oil level in the car.

However they are not always interchangeable when we refer to habitual actions. The following are possible:

I have to/I have got to leave home every morning at 7.30.

But when one-word adverbs of frequency (always, sometimes, etc.) are used have to is always preferable to have got to:

I often have to get up at 5. Do you ever have to get up at 5?

Must (not have to or have got to) is used in public notices or documents expressing commands:

Cyclists must dismount. Candidates must choose five questions.

We generally prefer Must you? to Do you have to?/Have you got to ? to mean Cant you stop yourself?

Must you always interrupt me when Im speaking?

Must is also used in pressing invitations, such as:

You really must come and see us some time.

and in emphatic advice, such as:

You really must take a holiday this year.

Even when heavily stressed, these uses of must do not mean or imply inescapable obligation.

Need as a modal

Need has only some of the characteristics of modal verbs in that it occurs in questions, Need you go?, and negatives, You neednt go. In Yes/No questions, a negative answer is often expected:

Need you leave so soon? (= surely not/I hope not)

Yes/No questions with Need? can be answered with must or neednt:

Need I type this letter again? Yes, you must./No, you neednt.

Need + have + past participle behaves in the same way:

Need you have told him about my plans?

You neednt have told him about my plans.

Yes/No questions with Need have ? can be answered:

Yes, I had to. (no choice)

No, I neednt have. (I had a choice)

Need as a modal verb also occurs in combination with negative-type adverbs like hardly, never, seldom, rarely and scarcely to make what are effectively negative statements:

She need never know what you have just told me.

I need hardly tell you how badly I feel about her departure.

All you need do is to take a taxi from the airport. (i.e. you need to do nothing except take a taxi)

Need can also occur in clauses with a negative main clause:

I dont think you need leave yet.

Need as a modal verb is mostly used in the negative (I neednt go) to express lack of necessity. Otherwise we generally use the full verb need to (used like any regular verb):

I need to/I needed to go to the dentist this morning.

I dont need to/I didnt need to go to the dentist.

When will you next need to go to the dentist?

Why did you need to go to the dentist? Etc.

Advisability/necessity: the present and future

Should, ought to, etc. refer to present time (except in indirect speech). With the addition of adverbials such as this afternoon, tomorrow, etc., they refer to future time.

Will/shall will combine with have to and need to (full verb) for explicit future reference:

Advisability/necessity: the perfect and past

Reference to the past can be made in the following ways:

Should have and ought to have could be followed (here) by but I wasnt/didnt to suggest that whatever was advisable or necessary did not happen:

I should have left London before 9, but I didnt.

Had to suggests that the action was performed in the past because this was necessary. It could be followed by and I was/did:

I had to leave London before 9 and I did.

The form had got to also exists, but it is not always suitable; had to is generally preferred.

When other tenses are required, appropriate forms of have to must be used to fill the gaps of the defective modal must:

I have had to remind him several times to return my book.

Because of the bus strike Ive been having to walk to work every day.

The reason for our late arrival was that we had had to wait for hours while they checked the plane before take-off.

If he had asked me, I would have had to tell him the truth.

Lack of necessity, inadvisability, prohibition

Examples of modal forms to express inadvisability, etc.

present lack of necessity  past lack of necessity

You neednt go there. You neednt have gone there.

Or: You dont need to go there.  (= you went there unnecessarily)

You dont have to go there. You didnt have to go there.

You havent got to go there. Or: You didnt need to go there.

(= there was no necessity to go there,

whether you did go or not)

present inadvisability  past inadvisability, not acted upon

You shouldnt start smoking. You shouldnt have started smoking.

You ought not to start smoking.  You oughtnt to have started smoking.

(but e.g. you ignored this advice)

present prohibition  failure to observe a prohibition

You cant park here.  You shouldnt have parked there.

You mustnt park here. You ought not to have parked there.

Shouldnt have and oughtnt to have are not ambiguous in the way that should have and ought to have can sometimes be ambiguous.

Have to can replace must in the present, but dont/didnt have to cannot replace mustnt in the present and past.

Lack of necessity: neednt/dont have to/havent got to

Lack of necessity can be expressed by neednt, dont have to and the more informal havent got to (where got is often stressed):

You neednt work such long hours.

You dont have to work such long hours.

You havent got to work such long hours.

(i.e. you can work fewer hours, if you choose to)

The above forms can be used to express the subjective point of view of the speaker that the listener has a choice or has permission not to do something. Note that havent to is a regional BE variation of dont have to.

Inadvisability prohibition: a scale of choice

We can use modals and other verbs to express inadvisability prohibition on a scale which reflects a degree of choice. This scale may vary according to the subjective view of the speaker. This is particularly the case when we are addressing others directly with you, or when we are referring to others with he, she, and they. At one end of the scale the advice (however strong) can be ignored. At the other end of the scale, the prohibition is total and, in the speakers opinion, there is no choice at all.

inadvisability shouldnt: generally means in my opinion, it is inadvisable to/

it is (your) duty not to.

oughtnt to: can be slightly stronger than shouldnt. It is

sometimes used to refer to regulations and duties

imposed from the outside. You oughtnt to park so

near the crossing suggests its your public duty not

to do this.

had better not: is stronger than shouldnt and oughtnt to. It is used

to recommend future action on a particular

occasion, not in general. It carries a hint of threat,

warning, or urgency: Youd better not overtake

here!

be to: can be used for instructions

cant: is nearly as strong as mustnt to suggest something

is prohibited: You cant park here.

prohibition mustnt: conveys absolute prohibition. In the opinion of the

speaker, there is no choice at all. This opinion may

be subjective or may be supported by some outside

authority, as in You mustnt turn left. (e.g. theres a

road sign forbidding it).

Mustnt, neednt, dont have to, havent got to

Though must, have to and have got to are generally interchangeable in the affirmative, dont have to and havent got to can never replace mustnt to convey prohibition. Like neednt they convey lack of necessity.

Mustnt conveys the strongest possible opinion of the speaker:

You really mustnt say things like that in front of your mother.

Julian mustnt hitchhike in Turkey on his own.

Prohibition reflecting external authority (e.g. in public notices, documents) is often expressed as must not (in full):

Life belts must not be removed.

Candidates must not attempt more than four questions.

Havent got to should be avoided with adverbs of frequency (always, sometimes, etc.) for reasons of style. So:

I neednt always be at the office by 9.

I dont always have to be at the office by 9.

is usually preferred to: I havent always got to be

Lack of necessity, etc.: present/future

Lack of necessity: neednt, dont have to, havent got to

Reference to present or future time can be made as follows. These forms are normally interchangeable:

Havent got to is not generally used with progressive forms.

Wont (and shant in BE) will combine with have to and need to (full verb) for explicit reference to the future:

I wont need to/have to be at the office before 9 tomorrow.

Inadvisability/prohibition: shouldnt/oughtnt to/mustnt, etc.

You shouldnt/oughtnt to/cant/mustnt be late for meetings. (present/habitual)

You shouldnt/oughtnt to/had better not/cant/mustnt be late tomorrow. (future)

Shouldnt, oughtnt to, had better not, cant and mustnt are used to refer to the future, although they do not have future forms. Possible alternatives are:

Shouldnt/oughtnt to/had better not can be replaced by:

It wont be advisable (for her) to play games for the next month.

Cant and mustnt can be replaced by:

We wont be allowed to park here for long.

You will be forbidden to enter the courtroom before 9.30.

Traffic in this street will be prohibited by law.

Lack of necessity/inadvisability/prohibition: perfect/past

Lack of necessity: neednt have, didnt have to, didnt need to

These forms can mean roughly the same thing in: e.g.

I neednt have gone to the office yesterday.

I didnt have to (or I didnt need to) go to the office yesterday.

(have and need are stressed)

(= I went there, but it was unnecessary)

When have and need are unstressed, they mean something different from neednt have:

I didnt have to/I didnt need to go to the office yesterday.

(= I knew it was unnecessary and I didnt go)

Because modals are defective, appropriate alternatives must be used in some tenses:

It wouldnt have been necessary to change at Leeds if we had caught the earlier train.

I havent had to cancel my appointment after all.

If he had asked me, I would have had to tell him the truth.

Inadvisability: shouldnt have and oughtnt to have

Both these forms suggest criticism of an action:

You shouldnt have paid the plumber in advance.

You oughtnt to have paid the plumber in advance.

or failure to observe a prohibition:

You shouldnt have/oughtnt to have stopped on the motorway.

Activities

Rewrite each sentence so that it contains the word in capitals, and so that the meaning stays the same.

a)      Im sure thats Marion.  WILL

Thatll be Marion

b)      Jim keeps giving me presents. WILL

c)      It makes no difference if we call it off. MAY

d)      Dont bother lying to me. HAVE

e)      The burglar might come back, so change all the locks. CASE

f)       Although its summer, the temperature is more like winter. MAY

g)      You should leave before Jack gets back. HAD

h)      That is not typical of Helens behaviour. WOULDNT

i)        It would be impossible to tell Sally the truth. POSSIBLY

Complete each sentence with a suitable word or phrase.

a)      What about this meat? Should/Shall I roast it or stew it?

b)      Thank you for offering but I possibly accept.

c)      Harry studies a lot. He know all the answers.

d)      Oh well, things much worse I suppose.

e)      Its no use waiting here. We well start walking.

f)       Jack refuses. He says its wrong and he do it.

g)      Any letters from Italy be for Tina.

h)      Cairo be quite cold in winter.

i)        I love these trees. Without them the garden the same.

j)       Rule 6. No member enter the bar area wearing sports kit.

Rewrite each sentence so that it contains the word in capitals, and so that the meaning stays the same.

a)      I expect this beach will be deserted. SHOULD

This beach should be deserted

b)      This climb is possibly dangerous. COULD

c)      Arthur is sometimes really irritating! CAN

d)      You cant borrow my car! WONT

e)      How about going to the theatre instead? COULD

f)       Do you want me to turn off the oven, or not? SHOULD

g)      I dont think Harry is likely to resign. WOULD

h)      Im not sure this isnt the way to Norwich.  CANT

i)        It would be all the same if we gave up now. MIGHT

j)       Please turn off the light before leaving. SHOULD

Choose the sentence closest in meaning to the sentence given.

a)      Its possible that well know the answers tomorrow.

A)    We may know all the answers tomorrow.

B)    We should know all the answers tomorrow.

b)      I dont think you should ring him now. Its rather late.

A)    You might not ring him now. Its rather late.

B)    Youd better not ring him now. Its rather late.

c)      You neednt come if you dont want to.

A)    You wont come if you dont want to.

B)    You dont have to come if you dont want to.

d)      I think its wrong for you to work so hard.

A)    You dont have to work so hard.

B)    You shouldnt work so hard.

e)      Perhaps these are the keys.

A)    These might be the keys.

B)    These must be the keys.

f)       I know. Why dont we go out to eat instead.

A)    I know. We must go out to eat instead.

B)    I know. We could go out to eat instead.

g)      It would be quite wrong for us to lock the cat in the house for a week.

A)    Wed better not lock the cat in the house for a week.

B)    We cant lock the cat in the house for a week.

h)      Its possible that the decision will be announced next week.

A)    The decision might be announced next week.

B)    The decision will be announced next week.

Complete each sentence with a suitable word or phrase.

a)      How funny that you should say that!

b)      The heating comes on automatically. You turn it on.

c)      The people here be really unfriendly.

d)      Of course Ill help! I possibly let you do it on your own.

e)      The team good without Sue at centre-forward.

f)       Of course you cant sleep if you drink so much coffee!

g)      Its a lovely hotel. And the staff more helpful.

h)      You be very critical sometimes.

i)        George it there if he has stayed there for so long.

j)       You right, but I still dont agree with you.

Insert the correct form of may/might except in 10 and 36, where a be allowed form is necessary.

It rain, youd better take a coat.

He said that it rain.

We as well stay here till the weather improves.

I borrow your umbrella?

You tell me! (I think I have a right to know.)

Candidates not bring textbooks into the examination romm.

People convicted of an offence (have a right to) appeal.

If he knew our address he come and see us.

I come in? Please do.

When he was a child he (they let him) do exactly as he liked.

I think I left my glasses in your office. You ask your secretary to look for them for me. (request)

He be my brother (I admit that he is) but I dont trust him.

I never see you again.

He be on the next train. We as well wait.

If we got there early we get a good seat.

The police (have a right to) ask a driver to take a breath test.

You ought to buy now; prices go up.

Ill wait a week so that he have time to think it over.

He isnt going to eat it; I as well give it to the dog.

You at least read the letter. (I think you should)

You have written. (I am annoyed/disappointed that you didnt.)

Wed better be early; there a crowd.

Nobody knows how people first came to these islands. They have sailed from South America on rafts.

You (have permission to) use my office.

He said that we use his office whenever we liked.

I dont think Ill succeed but I as well try.

You ought to go to his lectures, you learn something.

If we can give him a blood transfusion we be able to save his life.

Two parallel white lines in the middle of the road mean that you not overtake.

If I bought a lottery ticket I win $1000.

If you said that, he be very offended.

I wonder why they didnt go. The weather have been too bad.

Warning: No part of this book be reproduced without the publishers permission.

He has refused, but he change his mind if you asked him again.

I see your passport, please?

He (negative) drive since his accident. (They havent let him drive.)

Use must not or need not to fill the spaces in the following sentences.

You ring the bell; I have a key.

Notice in cinema: Exit doors be locked during performances.

You drink this: it is poison.

We drive fast; we have plenty of time.

You drive fast; there is a speed limit here.

Candidates bring books into the examination room.

You write to him for he will be here tomorrow.

We make any noise or well wake the baby.

You bring an umbrella. It isnt going to rain.

You do all the exercise. Ten sentences will be enough.

We reheat the pie. We can eat it cold.

Mother to child: You tell lies.

You turn on the light; I can see quite well.

You strike a match; the room is full of gas.

You talk to other candidates during the exam.

We make any more sandwiches; we have plenty now.

You put salt in any of his dishes. Salt is very bad for him.

You take anything out of a shop without paying for it.

You carry that parcel home yourself; the shop will send it.

You clean the windows. The window-cleaner is coming tomorrow.

Mother to child: You play with matches.

Church notice: Visitors walk about the church during a service.

I go to the shops today. There is plenty of food in the house.

You smoke in a non-smoking compartment.

Police notice: Cars be parked here.

Fill the spaces in the following sentences by using must, cant/couldnt or neednt + the perfect infinitive of the verbs in brackets.

must + perfect infinitive is used for affirmative deductions.

cant/couldnt + infinitive is used for negative deductions.

neednt + perfect infinitive is used for a past action which was unnecessary but was performed.

Did you hear me come in last night? No, I (be) asleep.

I wonder who broke the wineglass; it (be) the cat for she was out all day.

You (help) him. (You helped him but he didnt need help.)

I had my umbrella when I came out but I havent got it now. You (leave) it on the bus.

He (escape) by this window because it is barred.

I (give) $10. $5 would have been enough.

I saw a rattlesnake near the river yesterday. You (see) a rattlesnake. There arent any rattlesnakes in this country.

He is back already. He (start) very early.

He returned home with a tiger cub. His wife (be) very pleased about that.

I bought two bottles of milk. You (buy) milk; we have heaps in the house.

I phoned you at nine this morning but got no answer. Im sorry. I (be) in the garden.

I left my bicycle here and now its gone. Someone (borrow) it.

When she woke up her watch had vanished. Someone (steal) it while she slept.

Ive opened another bottle. You (do) that. Weve only just started this one.

The machine said You weigh 65 kilos and I said Thank you. You (say) anything.

I told him to turn left and he immediately turned right! He (understand) you.

Perhaps he swam across. No, he (do) that; he cant swim.

Do you remember reading about it in the newspapers? No, I (be) abroad at the time.

He (walk) from here to London in two hours. It isnt possible.

He was very sick last night. The meat we had for supper (be) good.

There was a strike and the ship couldnt leave port. The passengers (be) furious.

We went to a restaurant and had a very good dinner for $10. You (have) a very good dinner if you only paid $10.

I have just watered the roses. You (water) them. Look, its raining now!

That carpet was made entirely by hand. It (take) a long time.

The door was open. It (be) open. I had locked it myself and the key was in my pocket.

Rewrite each sentence so that it contains the word in capitals, and so that the meaning stays the same.

a)      It wasnt very nice of you not to invite me to your party! MIGHT

You might have invited me to your party!

b)      Thank you very much for buying me flowers! SHOULDNT

c)      It wouldnt have been right to let you do all the work on your own. COULDNT

d)      I dont believe that you have lost your keys again! CANT

e)      Mary was a talented violinist at the age of ten. PLAY

f)       Perhaps they didnt notice the tyre was flat. MIGHT

g)      The results are expected tomorrow. KNOW

h)      They escaped possible injury when the car crashed. HAVE

i)        A visa wasnt necessary after all. NEED

j)       Apparently someone has borrowed the cassette player. HAVE

Complete each sentence with a suitable word or phrase.

a)      Dont worry that Carol is late, she might/could have missed the train.

b)      I begged David to accept some money, but he hear of it.

c)      That was a lucky escape! You been killed!

d)      It was supposed to be a secret! You told her!

e)      I spent last week at the beach because I didnt go to school.

f)       The plane is late. It landed by now.

g)      You met my brother. I havent got one!

h)      There is only one solution. The butler done it.

i)        It was lovely. We a better holiday.

j)       So it was you who set off the fire alarm for a joke! I known!

Complete the comment at the end of each sentence.

a)      Pay no attention to what Martin said. He cant have been serious.

b)      Fancy accepting the job just like that! You asked me first!

c)      The rest was no problem at all. It easier, in fact!

d)      Im sure Jack didnt mean to ignore you. He noticed you.

e)      The meat is a bit burnt. You cooked it for so long. I did tell you!

f)       There were plenty of tickets left for the concert. We them in advance.

g)      Sally got home at four oclock this morning. The party really good!

h)      This homework is not as good as usual. I think you more time on it.

Put one suitable word in each space. Words with nt count as one word.

a)      I could have become a millionaire, but I decided not to.

b)      You have been here when Helen told the boss not to be so lazy!

c)      Peter wasnt here then, so he have broken your vase.

d)      I have bought the car, but I decided to look at a few others.

e)      If you felt lonely, you have given me a ring.

f)       Dont take a risk like that again! We have lost because of you.

g)      Its been more than a week! You have some news by now!

h)      We were glad to help. We have just stood by and done nothing.

i)        You really have gone to so much trouble!

j)       I have thought that it was rather difficult.

Complete each sentence with a suitable word or phrase.

a)      You should have seen Jims face! He happier!

b)      Im sorry. I suppose I been a bit rude.

c)      Surely it been Ann who told you.

d)      You really so much trouble over me.

e)      One thing is for sure, someone known about it.

f)       Was it really necessary? You to tell the police, you know.

g)      They saved her from the fire, but the ladder didnt reach her window.

h)      Keep your fingers crossed! The traffic warden noticed the car is parked on double yellow lines!

i)        Its funny bought exactly the same dress as me!

j)       I should would know better.

Rewrite each sentence so that it contains a modal auxiliary and so that the meaning stays the same.

a)      The police refused to do anything about my noisy neighbours.

b)      Jeans boss was extremely kind to her.

c)      Why didnt you back me up!

d)      Our worrying so much was a waste of time.

e)      Its just not possible for the cat to have opened the fridge!

f)       George knew how to ride a bicycle when he was five.

g)      I wanted to go to the party, but it was snowing hard.

h)      It would have been possible for Helen to give us a lift.

i)        Its possible that the last person to leave didnt lock the door.

j)       School uniform wasnt compulsory at my school.

Rewrite each sentence, beginning as shown, so that the meaning stays the same.

a)      Although you are in charge, it doesnt give you the right to be rude.

You may be in charge, but it doesnt give you the right to be rude.

b)      I recommend going to Brighton for a week.

I think

c)      Its typical of Steve to lose his keys!

Steve would

d)      I suppose Kate is quite well off.

I should ..

e)      I am as happy as possible at the moment.

I couldnt

f)       Although I tried hard, I couldnt lift the suitcase.

Try ..

g)      Im sure that Peter will be on time.

Peter is

h)      Fancy you and I having the same surname!

Its odd

i)        If I were you Id take up jogging.

I think .

j)       Do we have to leave so early?

Need ..