Modal verbs - an overview

Modal verbs are a type of auxiliary verb that gives 'modality' to the main verb, to express, for example: ability, probability, obligation or permission.

This post is not intended to be a lesson, but a sort of Ready Reference. It consists of three parts:

1. Introduction to modal verbs and some similar verbal expressions
2. Modal verbs listed by function
3. Modals listed by verb

Modals also have special uses which I haven't really gone into here, such as in conditionals, reported speech and future in the past. There are also no doubt some uses I've missed. If you spot any, please leave a comment.

Contents

Click on a function or verb to go to the relevant section.

1. Introduction	3. Modal and other verbs
The modal auxiliaries	can	could
Characteristics of modals	will	would
Aspect and time reference	shall	should
Other verbs with similar uses	may	might
2. Functions	must
Ability	ought to
Permission and requests	Semi-modals
Possibility and uncertainty	need to	dare
Probability and expectation	Others
Speculating and deduction	have to	used to
Obligation, necessity, prohibition	Semi-auxiliaries
Advice and recommendations	be going to	be to
Offers and suggestions	be able to	be allowed to
Willingness and refusal	be supposed to	be meant to
Habit and typical behaviour	be willing to	be + adj + to
Annoyance and criticism	had better

1. Introduction

The modal auxiliaries back to Contents

• can, could
• shall, should
• will, would
• may, might
• must
• ought to

Note - Some books list ought to as a semi-modal. But as it can't be used with do / does / did, and behaves just like the others, I'm including it as a full modal.

Characteristics of modal verbs back to Contents

Modal auxiliaries share four characteristics with the primary auxiliary verbs do, be, have

• they form their negatives with not or -n't

  He can't come till later.
  In fact he might not come at all.

• they have inverted question forms

  Could you do something for me?
  Will you give this to Peter?

• they can be used in short forms, short answers and tag questions:

  I'm not coming, but Sam might. (short forms)
  Who can tell me the answer? - I can. (short answers)
  You won't forget, will you?. (tag questions

• they can be stressed for emphasis

  But I can swim, honest.

They also have a few characteristics of their own:

• they're used with the bare infinitive (but see next section on aspect)
• they don't use do /does / did for negative or question forms (see above)
• they have the same form for all persons (no 3rd person singular s)
• they don't have different tense forms (but they can have different aspects - see next section). In their base form, they can often refer to the future as well as the present.

Modal verbs can have aspect back to Contents

They can theoretically be used in all four aspects, but not all modals are used in all aspects.

• simple - He may be in the kitchen
• continuous - He might be making the lunch
• perfect - He could have finished by now.
• perfect continuous - He really should have been serving it out by now

The verbs can and shall are usually only used in simple aspect. The four aspects of will form the basis of the future tenses.

Continuous aspect is often used to speculate or make deductions about what somebody is doing. Perfect aspect has two main uses: speculation and deduction about the past, and making comments, often critical, about a past action.

More detail will be given in the section for each individual verb.

Modal functions usually have two time references

Each modal function usually has two time references:

• present and future - these are formed with the base form of the modal verb:

  I can do it now
  I could do it tomorrow
  You should phone him now
  He might be out of town tomorrow.

• past - these are sometimes formed with a related modal, a modal perfect or a different verb altogether:

  She could swim almost before she could walk
  She must have been a quick learner
  She had to learn quickly

Overlap and double meanings

As modal verbs usually have more than one meaning, the same sentence can sometimes mean two different things, depending on context. For example, should can be used both for expectation and obligation

• Have you seen Judy? Have you tried her office, she should be here by now.
  (expectation / probability)
• Why in earth isn't Judy here. She should be here by now.
  (obligation - it's her duty)

Semi-modals plus back to Contents

There are two verbs which can be used both like modals and ordinary verbs, and so are often called semi-modals:

• need
• dare

And there are also two verbs which have some affinity with modal verbs. The verb used to was in the past used like a modal, but is now almost always used like an ordinary verb. The verb have (got) to is used to exprtess the modal meaning of obligation.

• used to
• have (got) to

All four of these verbs are (or can be) used with do / does / did in negatives and questions.

Semi-auxiliaries

We'll also look at a group of expressions based on the auxiliary verb be plus to, which are often used with modal meaning. And there's one based on had - had better.

• be going to
• be to
• be supposed / meant to
• be willing to
• be + adjective + to
  • be bound to
  • be sure / certain to
  • be likely to
  • be due to
  • be set to
• had better

2. Functions of modal verbs

There are many ways of categorising the functions of modal verbs, but I've divided them into ten main areas.

Negative functions are treated together with positive functions, so lack of ability is dealt with in the Ability section, lack of obligation in the Obligation section, etc.

Abilityback to Contents

In spoken English, we usually prefer, where possible, to use can and could rather than be able to, which is seen as more formal. But if we want to use another tense or combine it with another modal, such as will or used to,or another we need to use be able to.

actual ability - present

• can / be able to - ability in the present

  She can sing really well.
  She's able to dress herself now.

• can - ability right now (more common than able to)

  Look! I can swim!

potential ability - present and future

• can / could - potential ability

  I can / could do now if you like.

• can / could - ability in the future (when we decide now)

  I can / could do it next week.

• be able to - future ability

  Will you be able to come to our party?

lack of ability - present and future

• cannot - negative ability in the present and in future

  He can't swim at all.
  She can't come next weekend after all.

• not be able to - negative ability in the present

  I'm not able to help you, I'm afraid

• not be able to - negative ability in the future

  They won't be able to deliver before Thursday

actual ability - past

Notice the difference between the general past, where we can use could in positive statements, and specific occasions in the past, when we have to use be able to (or manage to), except with verbs of the senses and certain others.

• could / be able to - general ability in the past

  He could speak French like a native
  Could you ride a bicycle at that age?
  I was able to read before I went to primary school.
  She used to be able to juggle rather well.

• could - ability in the past on a specific occasion before see, hear, taste, feel, guess, understand, remember

  He could hear someone calling his name.
  She could understand exactly how he felt.

• be able to - ability in the past on a specific occasion

  We were able to find a nice little hotel.
  Were you able to solve the puzzle?
  Have you been able to find somewhere to stay?

• manage to - ability in the past on a specific occasion, especially when there was some difficulty involved

  Despite the problems, they managed to complete the project on time.
  Did you manage to fix the dripping tap?

potential ability - past

• could have - potential ability in the past not fulfilled - it would have been possible, but didn't happen.

  I could have come back yesterday, but decided to stay on for an extra day.
  I could have told you that yesterday. (But you never asked me!)

lack of ability - past

In negatives, we can use could not / couldn't, be able to for both general and specific, and not manage to for specific occasions.

• could not / not be able to - negative ability in the past - general

  She couldn't walk until she was two.
  He wasn't able to ride a bike until he was ten.

• could not / not be able to / not manage to - negative ability in the past on a specific occasion

  I couldn't find my keys.
  She wasn't able to fix the car.
  I'm afraid we didn't manage to find what you were looking for.

Permission and requests back to Contents

asking for permission

• can - asking permission (informal)

  Can I go now, please?

• could - asking permission (polite)

  Could I ask a question, please?

• may - asking permission (rather formal - some people think this is more 'correct')

  May I leave the table?

• might - asking permission (rather formal)

  Might I have a word with you?

giving permission

• can - giving permission

  You can stay out late as long as you let us know where you are.

• may - giving permission (more formal - especially written)

  Residents may park in the places provided.
  No more than four children may enter this shop at one time.

refusing permission / prohibition

• cannot - refusing permission

  No, you can't stay up late to watch the movie.
  Sorry, you can't park here.

• may not - refusing permission / prohibition (more formal - especially written)

  Guests may not have pets in their rooms.

talking about general permission

We use be allowed to to talk about general permision, in other words, laws and rules.

• be allowed to - talking about general permission in the present

  Only students are allowed to borrow books from this library.
  Are we allowed to smoke here?
  Cyclists are not allowed on the motorway.

permission in the past

As when talking about ability, we can only use could to talk about general permsiion in the past. For specific occasions, we need to use be able to.

• could / be allowed to - general permission in the present

  I could have friends around whenever I liked.
  We were allowed to go parties.

• be allowed to - a specific permission in the past

  I wasn't allowed to touch the exhibit.

negative permission in the past

• could not / not be allowed to - general permission in the past

  I couldn't stay out all night.
  We weren't allowed to make a lot of noise.

• not be allowed to - permission on a specific permission in the past

  She wasn't allowed to go to the rock festival as she was only fourteen.

requests - 1. asking someone to do something

Could and would are more polite than can and will, which are quite informal.

• can / could - asking someone to do something

  Can you help me with this, please?
  Could you lend me your paper, please?

• will / would - asking someone to do something

  Will you give this to your father, please.
  Would you tell him I called?

requests - 2. asking someone for something or if you can do something

These requests are rather similar to asking permission - could and may are more polite and might is more formal (and not often used)

• can / could / may /might -

  Can I have some of those oranges, please
  Could I try these on, please.
  May I have some more coffee, please?
  Might I have another of those delicious cakes?

Possibility and uncertainty back to Contents

possibility

• can - general possibility

  It can get really cold here in winter.
  Can it be true?
  How many people can fit into a Volkswagen Beetle?

• may / might / could - present and future possibility

  They may be coming tomorrow.
  I might be a bit late
  I could probably get off a bit earlier.

• may / might / could - general and theoretical possibility

  Some people may have difficulty understanding this concept.
  Small children might find this story frightening.
  There could be an answer.

• may well /might well / could well - more likely possibility

  That may well be the answer.You might well be right.
  That could well work.

• may just /might just / could just - less likely possibility

  That may just be the answer.You might just be right.
  That could just work.

• could always - emphasising the possibility of something happening

  They could always raise taxes without warning.

• could always - combining possibility with implied suggestion

  You could always talk to the boss.

uncertainty

• might not / may not - negative future possibility

  He might not come, of course.
  She may not want to speak to you herself.

logical impossibility

• cannot - negative possibility

  That clock can't be right, surely?

past possiblity

• could - general possibility in the past

  In those days the police could stop you for any reason.

• might have / could have - something that was possible in the past but didn't happen - often implies a criticism

  You might have fallen.
  We could have all been killed!

Probability & expectation back to Contents

expectations - things that are probably true

• should / ought to - expectations (often with be)

  There should be some milk in the fridge.
  He should be here any minute now.

• should / ought to - unfulfilled expectation (often with be)

  There isn't any milk. But there should be. I bought some yesterday.
  Shouldn't there be some instructions with it?
  There ought to be some sort of switch.

making predictions based on what we expect

• will (not) / would (not)

  We'll probably be about an hour or so.
  I'm sure he won't like it. It's just not his cup of tea.
  He would love to hear from you, I'm sure.

• shall (not) / should (not)

  I shall be staying for a week or so.
  We shan't be long.
  We shouldn't be back too late.

probability

• be likely to - probability

  He's likely to be late. He usually is.

• be due to - future expectation

  The government are due to make a statement tomorrow.

strong probability or certainty

• must - certainty, even though the evidence suggests something different - we stress must here.

  It must be there, I put it there earlier.

• can't - certainty against the evidence

  She can't be that old, surely!

• bound to - strong probability

  He's bound to make a good impression in that suit.

• certain to / sure to - strong probability

  City are certain to win the cup.
  They're sure to win.

• be to - expectation - quite formal, used especially in the media

  The government are to announce new measures tomorrow.

• due to - expectation

  The government are due to make a statement tomorrow.

• set to - expectation based on evidence

  United are set to win the championship.

Speculation & deduction back to Contents

speculating about the present and future

• might be / may be / could be - speculating about the present and future

  He might be stuck in a traffic jam.
  She may be trying to contact us.
  We could be lost.

• might not / may not (but not could) - negative speculation about the present and future

  She may not be able to hear you.
  They might not be at home.

speculating about the past

• might have / may have / could have - speculating about the past

  He might have missed his train.
  She may have done it already.
  They could have forgotten about it.

• might not have / may not have (but not could not have) - negative speculation about the past

  He mightn't have heard you.
  She may not have got our message.

deduction - making logical assumptions about the present

• must be - logical deduction about the present

  If they're not there they must be in the other drawer.

• can't be - logical deduction (negative)

  He can't be in Paris! I saw him this morning.

deduction - making logical assumptions about the past

• must have - logical deduction about the past

  We must have taken the wrong road.

• can't have / couldn't have - logical deduction about the past (negative)

  You can't have locked the door properly.
  She couldn't have got my message.

Obligation & necessity back to Contents

obligation

• must - internal or strong obligation in the present - the obligation usually comes from yourself or someone in authority - your parents, your boss etc, especially when they insist on something

  I must remember to speak to him tomorrow.
  You must tidy up your room immediately.
  Must I really do it now? Can't I do it later?

• must - strong obligation in instructions and notices

  Drivers must pay attention to other traffic at all times.
  Guests must vacate their rooms before midday.

• have to / have got to - external specific obligation - we use have got to mostly in spoken English. In formal written English we use have to

  She's got to be / She has to be at the station by seven.
  We've got to / We have to finish this today.

• have to - talking about general obligations which are usually external - we don't normally use have got to here.

  I have to be at work at nine every day.
  We have to separate the rubbish.

necessity

• need to - necessity

  You need to get a visa.
  We need to get some more milk.

obligation or necessity with will

• have to / need to - future obligation or necessity

  We'll have to finish this later.
  You'll need to tell me how you got on.

• have to / need to - asking about future obligation or necessity

  Will we have to get a taxi?.
  We won't need to revise too much, will we?.

obligation not to / prohibition

• cannot - prohibition

  You can't park here.

• must not - prohibition

  Passengers must not distract the driver.
  You mustn't go too near the railway.

lack of obligation or necessity

• not have to - lack of obligation

  We don't have to go to school today.
  You won't have to ask permission, will you?

• not need to - lack of necessity

  You needn't come / don't need to come if you don't want to.

obligation and necessity in the past

We can't use must for past obligation or necessity, only have to or need to.

• have to - general obligation in the past

  In the past you had to have a radio licence.
  Did people have to do military service at that time?

• have to - personal obligation or necessity in the past

  We had to book in advance.
  Did you have to wait long?

• need to - necessity in the past

  We needed to pay by credit card.
  Did you need to make an appointment?

lack of obligation or necessity in the past

• not have to / not need to - lack of obligartion or necessity in the past which we knew about so didn't do

  We didn't have to dress formally. (So we didn't).
  They didn't need to pay in advance. (So they didn't)

• not have to / not need to - lack of obligation or necessity in the past which we knew about but did anyway

  We didn't really have to dress up, but we did anyway fot the fun of it.
  They didn't need to pay in advance, but they preferred to do it anyway.

• need not have - lack of necessity in the past which we didn't know about at the time (so we did whatever it was), and only later discover was unnecessary.

  We needn't have left so early, we had plenty of time. (But we did leave early)

Advice & recommendation back to Contents

advice

• should / ought to - giving advice

  You should take more exercise.
  You ought to get out more.
  You shouldn't talk to him like that.
  She oughtn't (to) take it seriously.

• shall / should - asking for advice or confirmation

  Shall / Should I put these things down here?
  What shall I do?
  Where should I go?

• should have /ought to have - advice after the fact

  You should have asked my advice before you decided.
  You ought to have booked earlier.

• would - giving advice

  I'd accept his offer, if I were you.
  I wouldn't do it myself, personally.

• I should - giving advice (British English)

  I should take the job, if I were in your shoes.
  I should't worry about it too much, if I were you.

• had better - stronger or more urgent advice than should or ought to (including to ourselves)

  You'd better let him know right away.
  I'd better have another look at this report.

• must - strong advice

  You must listen to what the doctor says.

recommendation

• should /ought to - recommendation

  You should try that new restaurant.
  You really ought to see the new exhibition, it's great

• must - strong recommendation

  You really must see this new film.

Offers & suggestions back to Contents

offers

Could and should are more tentative than can and shall.

• can / could - offers

  Can I carry that for you?
  I could carry that for you, if you like.

• shall - offers

  Shall I make you another cup of tea?

• may - polite offers

  May I help you?

• will - offers

  I'll give you a lift to the station.

• would you like

  Would you like me to take that for you?

suggestions

• could - making a suggestion

  You could try asking Jim.

• shall - making and asking for suggestions

  Shall we take a taxi?
  What shall I do with these boxes?

• should - making a suggestion - usually used in negative questions, and asking for suggestions

  Shouldn't we be going? It's getting quite late.
  Where should I put the vegetables?

• might - making a suggestion

  You might want to check your spelling.

Willingness and refusal back to Contents

willingness in the present and future

• will - willingness

  She'll help you, I'm sure.

• will / would - polite instructions and requests

  If you'll just follow me.
  Would you hold this for me, please?

• be willing to - willingness

  I'm perfectly willing to go with you.

refusal or unwillngness

• will not - refusal or unwillingless

  No, I won't help you.
  He just will not so what he is told.
  This door won't open.

• not be willing to - refusal or unwillingness

  He's not willing to change the arrangements
  They won't be willing to help.

willingness in the past

• would - general willingness in the past (related to past habit)

  He would always do as I asked.

• be willing to - general willingness in the past (use would for specific occasions)

  She was always willing to give me a hand.

refusal or unwillingness in the past

• would not - refusal in the past - general and specific

  He would never lift a finger around the house.
  The car wouldn't start again.

• not be willing to - refusal or unwillingness - general or specific

  He was never willing to tell you exactly what he thought.
  She wasn't willing to postpone the meeting.

Habit and behaviour thought typical back to Contents

habit in the present

• will - general habit

  He'll always buy her flowers for their anniversary.

habit in the past

• would - for past habits but not past states

  I would walk to work every day.
  She would always bring us presents when she came to visit.
  He would wander around absent-mindedly as if in a dream.

• used to - past habits or states that's not true today

  She used to live in London, but now lives in New York.
  I used to take the metro to work, but now I cycle.

typical behaviour

• will - commenting on typical behaviour (often showing annoyance), often with keep

  He will keep asking me these stupid questions.
  You will keep interrupting me!
  Well, if you will keep turning up late, what do you expect?

• would - commenting on something someone has done which is seen as typical of their behaviour (often showing mild annoyance or criticism)

  Well, she would say that, would't she! That's just typical of her.
  He would turn up just as we were about to leave.
  You would have to say that to his face, wouldn't you?

Annoyance and criticism back to Contents

expressing annoyance and criticism about the present

• can - expressing annoyance

  He can be so annoying at times!

• could - expressing annoyance when someone doesn't do something

  You could call me once in a while!

• might - expressing annoyance when someone doesn't do something

  He might let me know when he's going to be late!

• have to / must - used in questions - must is stronger

  Do you have to make so much noise?
  Must we go through all this again?

• will - expressing annoyance about typical behaviour

  She will just totally ignore everything I say.
  You will make those horrible noises while I'm trying to read.

• would - expressing annoyance (also commenting on typical behaviour)

  Well, she would say that, would't she! That's just typical of her.
  To tidy up once in a while. Would that be asking too much?

expressing annoyance and criticism about the past

• could have / might have - critical comment

  You could have had an accident.
  We might have all been killed.

• could have / might have - expressing annoyance

  You might have told me earlier.
  She could have sent us a not, at least.

• should have / ought to have - expressing annoyance or criticism

  You should have taken my advice.
  They ought to have done something about it by now!
  You should have handed in your essay last week.

• would not have - expressing annoyance

  It wouldn't have hurt her to visit us now and then.

2. Modal and other verbs with a similar function

Full modals

can back to Contents

• ability in the present

  She can sing really well.

• ability in the future (when we decide now)

  I can do it next week.

• ability right now

  Look! I can swim!

• possibility

  It can get quite cold at this time of year.
  Can it really be true?

• asking permission

  Can I go now, please?

• giving permission

  You can stay out late as long as you phone us.

• offers

  Can I carry that for you?

• requests

  Can you help me with this, please?

cannot

• negative ability in the present and in future

  He can't swim at all.
  She can't come next weekend after all.

• negative possibility

  That can't be the time already

• prohibition

  Sorry, but you can't park there.

• deduction

  That can't be him already.

• refusing permission

  No, you can't stay up late to watch the movie.

can't have

• negative deduction about the past

  He can't have been there. He was in Paris.

could back to Contents

• general ability in the past

  He could speak French like a native

• possibility

  I could probably get off a bit earlier.

• polite requests

  Could you hold this for me, please?

• asking permission

  Could I borrow the car this afternoon?

• offers

  I could carry that for you, if you like.

• making a suggestion

  You could try asking Jim.

• speculation

  There's someone at the door. It could be Peter from next door.

• expressing annoyance

  You could have called!

could not

• negative ability in the past - general and on a specific occasion

  She couldn't walk until she was two.
  I couldn't find my keys.

• negative ability in the present

  I couldn't walk another hundred metres.

• prohibition in the past

  When we were children we couldn't leave the table without permission.

could be + -ing

• present possibility, perhaps suggesting advice

  You could be doing your homework now.

• speculation about the present

  She could be doing it right now.

could have

• speculating about past possibility

  She could have missed her train.

• critical comment or expressing annoyance

  You could have had an accident.
  He could have told me he was going to be late!

could not have

• past impossibility

  I couldn't have gone faster if I'd tried.

• deducing that something didn't happen

  She couldn't have got my letter.

could have been + -ing

• making a comment about an activity not done in the past

  You could have been doing your homework while you were waiting for Pete to come round.

may & might (not)back to Contents

• possibility

  They may be coming tomorrow.
  I might be a bit late
  She may / might not come at all.

• asking permission (rather formal)

  May I leave the table?
  Might I be excused? (even more formal)

• polite requests (rather formal)

  May I have some more cake?
  Might I have another of those delicious cakes? (even more formal)

may (but not might)

• giving and refusing permission

  You may leave the table now.
  No, you may not stay out until all hours of the night!

• polite offers

  May I help you?

might (but not may)

• past of may in reported speech

  She said she might be a bit late.
  The told us they might not be here befote ten.

• expressing annoyance

  He might let me know he's going to be late!

• suggestions

  You might want to check your spelling.

may / might be + -ing

• speculating about the present and future

  He might be working on it as we speak.
  She may be coming tomorrow.

may / might have

• speculating about past possibility

  She may / might have done it already.
  They may /might not have heard you.

might have (but not may have)

• expressing annoyance

  You might have told me earlier

may / might have been + -ing

• speculating about a past activity

  She may / might have been doing it when we phoned.

may / might (not) (have) for concession

• making one point while conceding another

  He may / might be very intelligent, but he doesn't seem to have a lot of common sense.

• making one point while conceding another

  They may / might not be rich, but they certainly know how to enjoy themselves.

• making one point while conceding another

  It may / might well have been her idea, but it was me who did all the work.

must back to Contents

We use must for a personal obligation, and have to for a more general external obligation. We can't use must in the past and future, and need to use have to instead.

• internal or strong obligation in the present

  You must tidy up your room immediately.
  I must speak to him tomorrow.

• necessity

  You must turn it on first.

• speculation or deduction about the present

  He must be about forty, I would think.

• strong recommendation

  You really must see this new film.

• expressing annoyance (in questions)

  Must you make so much noise while I'm on the phone?

must not

• prohibition

  You mustn't touch that, it's very hot.

• strong advice

  You mustn't worry. I'm sure everything will work out OK.

must be + -ing

• making a deduction about a present or future activity

  He's making a lot of noise. He must be making something.
  She's not doing it today, so she must be doing it tomorrow.

must have

• making a deduction about past probability

  He must have missed the train.
  I must have left my mobile at home.

must (not) have

• talking about necessity

  You must have worked here for at least six months before you are entitled to holiday leave.
  You mustn't have been late more than tree times or they deduct it from your pay.

must have been + -ing

• making a deduction about a past activity

  There were clothes everywhere. She must have been doing the ironing.

shall - with I and weback to Contents

• suggestions

  Shall we take a taxi?

• offers

  Shall I make you another cup of tea?

• asking for advice or suggestion

  What shall we do next?

• question tag after let's and after will for offers

  Let's have a look at your sore knee, shall we?
  I'll do that, shall I?

• instead of will in 1st person (British English - apparently a bit old fashioned, but I use it from time to time) - for predictions, intentions etc

  I shall tell him tomorrow.
  We shall just have to see, won't we?
  I shall tell you what I've decided tomorrow.

shall be doing and shall have done - with I and we

In British English, we can use shall instead of will with I and we in other future tenses as well, although this isn't very common nowadays.

• other future tenses

  We shall be staying with our grandparents (= future continuous)
  We shan't be staying long.
  I shall have finished it by tomorrow. (= future perfect)
  If it's successful, we shan't have been doing all this work in vain. (= future perfect continuous)

shall - for other persons

• in legal and official or formal language

  The tenant shall pay rent monthly, one month in advance
  Candidates shall stop writing immediately I tell them to.

should (& ought to) back to Contents

The uses of should can be divided into two groups:

• when should and ought to are interchangable. This is the more common category.
• when should has special meanings which can't be expressed by ought to. These are less common, and more associated with British English.

should / ought to

• recommendations

  You should try that new restaurant.
  You really ought to see the new exhibition, it's great.

• making a suggestion - usually used in negative questions

  Shouldn't we be going?
  Oughtn't we say Goodbye?

• advice

  You should take more exercise
  You ought to get out more
  

should be / ought to be + -ing

• saying what is supposed to be happening

  You should be writing that report I gave you to do.

• speculating what is happening

  He should be sitting at home by now.

should have / ought to have

• comment on past action

  You should have told me earlier.
  You shouldn't have spoken to him like that.
  You ought to have have seen his face when he found out.

• making a suggestion about a past action - usually used in negative questions

  Shouldn't we have told them about it?
  Oughtn't we to have shut the gate?

should have been / ought to have been + -ing

• commenting on what was supposed to have been happening but didn't

  She should have been studying instead of gallivanting round town.
  You ought to have been paying more attention.

Other uses of should

As the past of shall

• In reported speech:

  She asked if we should get a taxi.

In some that clauses:

• in that clauses after certain verbs expressing importance

  She insisted that I should be at the meeting
  He recommended that we should consult a specialist.

• in that clauses after certain adjectives expressing importance

  It is vital that the work should be finished by the end of the week.
  It is essential that she should give me an answer today.

In American English (and occasionally in very formal British English), should is left out in these type of subordinate clauses to give a present subjunctive:
It is essential that she give me an answer today..
In informal British English, standard verb forms are often used:
It is essential that she gives me an answer today.

• In that clauses expressing surprise or personal reaction

  It's surprising that she should have behaved like that.
  I'm sorry that you should think I'd do a thing like that.

In American English would is more usual (and is also possible in British English)
I'm sorry that you would think I'd do a thing like that..

In conditionals

• Making first conditionals and time clauses more tentative. (This can be inverted)

  If you should happen to see him, could you give him this?
  Should I see him later, I'll tell him what you said.
  In case you should get lost, here's our number.

Instead of would in the first person

• giving advice

  I shouldn't go in just yet, if I were you.

• describing what you would do in certain circumstances (formal)

  If he spoke to me like that again, I should just walk out.

• in polite requests (quite formal)

  I should like to go now, if you don't mind.
  We should be grateful if you could give us a reply by the end of the week.

• giving an opinion about things you're not totally certain of

  I should think this will be enough for all of us.
  Will we be there in time for tea? - I should think so.
  You won't be very late, will you? - I shouldn't think so, no.

To express annoyance, surprise

• after how, why, who etc to express irritation, annoyance or surprise

  How should I know where he is?
  Why should I lift a finger to help him after what he did?
  Who should I see in town but your ex!

will back to Contents

Specifically about the future:

• stating future facts

  This shop will be closed tomorrow for stocktaking.

• expressing future intentions just decided on

  I'll ask her tomorrow.

• predictions about the future

  It'll probably rain later
  Do you think you'll be late?
  I'm sure she won't do anything silly.

About the present, general time and the very near future

• personal decisions made at the time of speaking

  I think I'll have another coffee.
  We're running a bit late. I'll ring for a taxi.
  I won't have any more, thanks.

• stating facts

  This car will only run on unleaded petrol

• predictions about the present

  That'll be him at the door now.

• stating inherent ability - somewhere between a fact and a prediction

  This will last us to the evening.

• requests

  Will you give this to your father, please?

• offers

  I'll give you a lift to the station if you like.

• asking and agreeing to do something

  Next time you see him will you tell him I was asking for him?
  OK. I'll tell him when I see him tomorrow.

• willingness

  She'll help you, I'm sure.

• habitual actions

  She'll always greet you with a smile.

• annoying habits (often with keep)

  He will keep talking all through the film. It's so annoying.

• making orders and instructions softer, especially with have to and need to - a form of distancing

  I’m afraid you’ll need to rewrite this report. (eg your boss)
  I’ll have to ask you to come with me, Sir. (eg Customs official)
  That will be £20, please. (eg shop assistant, saying what is owed)

• obligation and orders

  All pupils will assemble in the main hall immediately.

will not / won't

• refusal

  No, I won't help you.
  He just will not do what he is told.
  This photocopier won't work.

will be + -ing

• future continuous to talk about an expected future event

  I'll be arriving at about eight.

will have + pp

• future perfect to predict events being completed by a time in the future

  She'll have finished it by Thursday.

• making logical predictions about the present or recent past

  She won't have arrived yet.
  Give them a ring. They'll have finished their dinner by now.

will have been + -ing

• future perfect continuous to talk about how long activities will have lasted by a time in the future

  If a bus doesn't come soon I'll have been waiting for half-an-hour.

would back to Contents

• polite requests

  Would you hold this for me, please.

• giving advice

  I'd accept his offer, if I were you.
  I wouldn't do it myself, personally.

• conditional willingness

  If you told me what the problem was, I would be able to help.

• expressing annoyance (also commenting on typical behaviour)

  Well, she would say that, would't she! That's just typical of her.

• for past habits but not past states

  I would walk to work every day.
  She would always bring us presents when she came to visit.

• general willingness in the past (related to past habit)

  He would always do as I asked.

• as the past of will in reported speech

  He said he would be a bit late.

• future in the past

  This was the man who would one day become her husband.

would not / wouldn't

• refusal in the past

  He would never lift a finger around the house.
  The car wouldn't start again.

would be + -ing

• conditional willingness in the present

  I'd be doing it now if I had the right tools.
  I wouldn't be working here now if I hadn't done well at university.

would have + pp

• conditional willingness in the past

  I would have known if I'd met him before.
  She would never have come if we hadn't offered her a big increase in salary.

would have been + -ing

• conditional willingness starting in the past

  I would have been doing it now if you hadn't asked me to do something else.

Semi-modals plus

have to / have got to back to Contents

have to and must - We use have to for a general external obligation and must for a more personal obligation. We need to use had to instead of must for the past and have to with will.

have to and have got to - these both have exactly the same meaning, but have got to is used more in spoken English and have to in more formal written English. We can only use have got to in a present structure. For the past and with will, we need to use had to and will have to.

• external obligation - general rules

  I have to be at work at nine every day.
  We have to separate the rubbish.

• external obligation - specific occasion

  I have to go / I've got to go to the dentist's this afternoon.
  We have to / We've got to be there at eight.

• past and future obligation

  She had to leave early.
  We'll have to leave early

not have to / haven't got to

• lack of obligation - present

  We don't have to go to school today,
  I haven't got to do it after all.

• lack of obligation - past and future

  She didn't have to sit the exam.
  You won't have to ask permission, will you?

• expressing annoyance (in questions)

  Do we have to watch this film; it's so boring?

used to back to Contents

• past habit or state that's not true today

  She used to live in London, but now lives in New York.
  I used to take the metro to work, but now I cycle.

• question form (without -d)

  Did you use to live somewhere else?
  Didn't you use to have longer hair?

• negative form (without -d)

  She didn't use to be as rude as she is now.

Historical note - in questions and negatives nowadays we use do / does / did, but in British English modal forms are possible, although thought to be old-fashioned or very formal. You might come across the following modal forms:

1. Used she to sing as well as she does now?
   He used not (usedn't) to care so much about his appearance.
   Used they not (Usedn't they) to live in Barchester?

need to back to Contents

This is a semi-modal verb. It can have a modal structure in negatives and questions, but the normal structure with do / does / did is more common.

• necessity

  You need to get a visa.
  We need to get some more milk.

• necessity - questions

  Do we need to get any food? (normal form)
  Need we really go so early? (modal form)

not need to / need not

• lack of necessity or obligation in the present and future

  You don't need to come if you don't want to. (normal form)
  You needn't do it if you don't want to. (modal form)

did not need to / need not have

Notice the difference between didn't need to do something and needn't have done something. In the first we knew it wasn't necessary. Whether we then did it or not depends on the context. In the second, we only found out that it wasn't necessary after we had done it.

• lack of obligation in the past - known

  We didn't need to book a table, so we didn't bother.
  We didn't really need to book a table, but we did anyway.

• lack of obligation in the past - unknown

  We needn't have rushed. There are plenty of seats left.
  Oh you needn't have come to pick me up. I could easily have got a taxi.

dare back to Contents

• as a normal (non-modal) verb, with the pattern verb + obj + to-infinitive

  I dare you to tell him.

• as a modal in negatives

  I don't dare ask him again. (normal form)
  I daren't ask him again. (modal form)
  She dared not tell anyone about it. (literary or formal)

• as a modal in certain idioms

  Don't you dare tell him!
  How dare he talk to me like that?
  I dare say you're right. (especially British English)

semi-auxiliaries

be going to back to Contents

• for plans and intentions - very common in spoken language

  I'm going to get my hair cut tomorrow
  Do you think she's going to apply for that new job?
  They're going to build a new playground in the park.

• for predictions based on evidence

  Look at the way he's driving. He's going to have an accident if he's not careful
  Look at the time. We're going to be late if we don't get a move on.

was / were going to

• in reported speech

  She asked if you were going to visit her soon.

• future in the past

  I was going to do it but I didn't have time.

be to back to Contents

• obligation - instructions

  All students are to gather at the meeting place.

• obligation - relaying instructions

  We're to tidy up after us.

• obligation - expectations (in newspaper reports)

  The government are to announce new regulations tomorrow

be able to back to Contents

When possible, we prefer to use can (be able to. is more formal) But when talking about the past or with will, we have to use be able to.

• present ability

  She's able to dress herself now.

• ability in the past - general and on a specific occasion

  I was able to read before I went to primary school.
  We were able to find a nice little hotel.

• future ability

  Will you be able to come to our party?

be allowed to back to Contents

• permission

  Are we allowed to smoke here?

• general and specific permission in the past

  We weren't allowed to smoke at school.
  I wasn't allowed to touch the exhibit.

be supposed / meant to back to Contents

supposed to and meant to have the same meaning, saying what should happen, but often implying that a rule is not always followed.

• intended obligation

  We're supposed to tidy up after us.

• intended obligation

  He's meant to be in a meeting.

Use of supposed to and meant to in the past suggest that the action didn't happen.

• intended obligation in the past

  She was supposed to finish it last week, but I haven't seen anything yet.
  We were supposed to be there ten minutes ago.

• intended obligation

  He was to meant to be phoning me, but I haven't heard anything from him.

be willing to back to Contents

• willingness

  I'm perfectly willing to go with you.
  I'm afraid I'm not willing to discuss this any futher.

be + adjective + to back to Contents

• bound to - strong probability

  He's bound to win

• certain to / sure to - strong probability

  They're certain to win
  They're sure to win

• likely to - probability

  He's likely to be late. He usually is.

• due to - future expectation

  They're due to close this station next year.
  The train is due to arrive any moment.

• set to - probability based on past evidence - often used in the media

  They're set to win the championship

had better back to Contents

• giving strong advice (including to ourselves)

  You'd better let him know as soon as possible.
  I'd better get a move on, it's getting late.

• making a suggestion

  We'd better book early before it gets sold out.
  Hadn't we better take a closer look at this?

Related posts

• Modals for ability
• Shall and will
• The twelve tense system

Links

• Encyclopaedia.com - from the Concise Oxford Companion to the English Language - very interesting but a bit technical
• Wikipedia
• Grammar.About
• NICE - UCL
• Gramarring