Modal verbs: Level b

ABILITY

Can /be able to

(ability in the present/future)

Ann can type fast.

I will be able to pay you next week.

Could/was able to (=managed to – ability in the past) “Could” is more usual than “was able to”.

I could / was able to go on a trip round the city last week.

POSSIBILITY

May/might/could + present infinitive (perhaps; it’s possible that something will happen in the future or perhaps it is true at the moment)

May/might/could + perfect infinitive

(perhaps something happened in the past)

Could + perfect infinitive is used for smth which was possible but didn’t actually happen.

Sam may/might/could pass his test this time. (It’s possible that he will pass the test.)

She looks miserable. She may/might /could have lost her job. (Perhaps she has lost her job.)

Don’t drive so fast! You could have killed that man. (Luckily, you didn’t kill this man.)

PROBABILITY

Ought to/should + present infinitive show that something is probable now or in the future

Ought to/should + perfect infinitive show that something was likely to happen but we don’t know if it happened or not

Tom ought to/ should pass his exams. (He will probably pass.)

Has Nancy phoned yet? She ought to/ should have phoned an hour ago. (We don’t know whether she phoned or not.)

LOGICAL ASSUMPTIONS

Can’t/couldn’t + present infinitive

(I don’t think; it’s logically improbable)

Must + present infinitive (I think, I’m fairly sure; it’s logically probable)

can’t is opposite of must

can’t/couldn’t + perfect infinitive (It’s impossible that something happened in the past.)

must + perfect infinitive (It’s very probable that something happened in the past.)

She can’t be rich. Her house is too small. (I don’t think she’s rich.)

His face is red. He must be very angry. (I think he is very angry.)

It can’t be true. It must be a lie.

She can’t / couldn’t have lost her way; she must have missed the train. (= I don’t think she’s lost her way; I think she has missed the train.)

To express possibility in questions we don’t use may. We use: Can he? Could he? Is he likely to? Is it likely that? Might he? (Is it possible that?)

PERMISSION

(asking for permission)

can (informal) could (more polite)

may (formal) might (more formal)

Can/Could I interrupt you for a second?

May/Might I speak to the manager?

(giving or refusing permission)

can (informal; giving permission)

may (formal; giving permission – also used in written notices or formal announcements)

mustn’t/can’t (informal – refusing permission)

may not (formal – refusing permission)

Can I use your phone? – Of course you can. (informal)

Could I use your phone? – Of course you can. (not: of course you could)

May I use your phone? Certainly you may. (formal)

Luggage may be left here. (written notice)

I’m afraid you can’t/mustn’t enter the room.

Rubbish may not be left here. (written notice)

(talking about permission)

can/be allowed to (to talk about the future and present)

could (to talk about the past –used for repeated actions)

was/were allowed to (to talk about the past – used for repeated or single actions)

couldn’t/wasn’t allowed to (in negations or questions for either repeated or single actions)

Pupils are allowed to / can use the school swimming pool free of charge.

She was always allowed to/ could always play with her dolls after school. (repeated actions)

The reporter was allowed to (not: could) take a photo of the pop singer. (single action)

The foreigner wasn’t allowed to/couldn’t enter the country without a visa. (single action)

REQUESTS – OFFERS – SUGGESTIONS

Requests (asking someone to do smth)

Can you? (informal request)

Will you? (familiar)

Could you? (polite request)

May I? (formal request)

Would you/ would you mind? (more polite and formal than “could you”)

Can you help me, please?

Will you get me my glasses, please?

Could you make me some tea?

May I have a glass of water? (request)

May I open the window?(asking for permission)

Would you post this letter for me?

Would you mind typing these letters for me?

Offers (offering to do smth)

I’ll (I’m willing to do smth - informal)

Shall I/we / Can I/we (Do you want me/us to…? - informal)

Would you like/ Would you like me to…?

I’ll do the shopping if you like.

Shall I help you with your luggage?

Would you like some more tea?

Suggestions (making suggestions)

Shall I/we?

I/We can/could

We also express suggestions with:

Let’s? How about? Why don’t we? What about?

Shall we go to the theatre?

We can /could go to the club if you like.

Let’s go to the park. How about going to the park?

ADVICE – CRITICISM

Advice (saying what the best thing to do is)

should/ ought to + present infinitive

(ought to is sometimes used for advice based on laws, rules or generally accepted ideas)

Shall I? (asking for advice)

had better (advice for a specific situation)

You should stop smoking. (general advice)

You ought to treat animals kindly. (Most people believe this.)

Shall I tell him the truth?

You’d better call your parents or they’ll worry.

Criticism (saying what the best thing to do in the past was)

should/ ought to + perfect infinitive

You shouldn’t have been rude to her yesterday. (but you were)

You should have locked the car before leaving. (but you didn’t)

NECESSITY – OBLIGATION – PROHIBITION

Obligation- necessity

Must/have to (it’s necessary, I’m obliged to)

Must is used only in the present and future when the speaker decides.

Have to is used when the necessity comes from the outside the speaker or when others decide for him/her.

Have got to (more informal and usual than “have to”) is used for obligation on a single occasion.

Ought to (duty; It’s the right thing to do but people don’t always do it.)

Need (it’s necessary) is followed by a passive full infinitive or an –ing form and takes –s in the 3^rd person singular in statements.

I must lose some weight. (I say so.)

I had to go to work early yesterday. (“Must” is not possible here as it is used only in the present.)

I have to lose some weight. (The doctor says so; the doctor decides for me.)

I’ve got to tidy my room; Mother is angry.

I’ve got to phone her; she’ll be worried.

We ought to respect the environment. (but we don’t always do it)

Your hair needs to be cut. or Your hair needs cutting.

Must is used only for the present and future situations. Have to forms its questions and negations with do/ does and did.

Did you have to stay late at work yesterday? Yes. I had to type some urgent letters.

Absence of necessity

Needn’t + bare present infinitive /don’t have to/don’t need to (it is not necessary in the present or future)

Didn’t need to/didn’t have to (It wasn’t necessary in the past and we may not know if the action happened or not.)

Needn’t + bare perfect infinitive (We know that something happened in the past although it was not necessary.)

You needn’t take a jacket. It’s rather warm.

You don’t have to/ don’t need to take a jacket. It’ rather warm.

He didn’t need/ have to buy any milk. There was a lot in the fridge. (I don’t know if he bought any.)

She needn’t have bought any milk. There was a lot in the fridge. (I know she bought some milk but there was no need.)

Prohibition

Mustn’t (it’s forbidden)

Can’t (you aren’t allowed to)

You mustn’t enter the room.

You can’t wait here.