III. MODAL VERBS (Modal Auxiliary): a set of verbs which are used with other verbs to express (one of the modalities): possibility, ability, likelihood, certainty, obligation, etc., of the action. English modals include: can, could, may, might, must, ought to, shall, should, will, would…

The use of modal auxiliaries:

CAN:

1. Ability (be able to, be capable of, know how to):

- He can speak English but he can not write it very well.

2. Permission (be allowed to, be permitted to – can is less formal than may in this sense):

- Can I smoke in here?

3. Theoretical possibility (Contrast may = factual possibility)

- Anybody can make mistakes. The road can be blocked.

COULD:

1. Past ability: I never could play a banjo.

2. Present or Future Permission: Could I smoke in here?

3. Present Possibility (theoretical or factual): We could go to the concert. The road could be blocked.

4. Contingent possibility or Ability in unreal conditions: If we had more money, we could buy a car.

MAY:

1. Permission (be allowed to – in this sense, (be allowed to – in this sense, may is more formal than can. Instead of may not or rare mayn’t, the stronger mustn’t is often used in the negative to express prohibition): You may borrow my car if you like. You mustn’t borrow my car (you are not allowed)

2. Possibility (usually factual): The road may be blocked.

MIGHT:

1. Permission (rare): Might I smoke in here?

2. Possibility (Theoretical or factual): What you say might be true. We might go to the concert.

SHALL:

1. Willingness (on the part of the speaker in 2nd and 3rd person. Restricted use): He shall get his money. You shall do exactly what you wish.

2. Intention (on the part of the speaker, only in 1st person): We shall overcome. We shall let you know our decision.

3. Insistence (Restricted use): You shall do as you say. He shall be punished.

4. Legal & Quasi-legal injunction: The vendor shall maintain the equipment in good repair.

SHOULD:

1. Obligation & Logical necessity (ought to): You should do as he says. They should be home by now.

2. ‘Putative’ use (after certain expressions, e.g., ‘it is a pity that…’, ‘I am surprised that…’): It is odd that you should say this to me. I’m sorry that this should have happened.

3. Contingent use (1st person only and especially BrE) in main clause (=would): We should(would) love to go abroad (if we had the chance)

4. In rather formal real conditions: If you should change your mind, please let us know.

WILL:

1. Willingness (used in polite requests): Will you please open the window? Will you give me the key?

2. Intention (usually contracted ‘ll, mainly 1st person): I’ll write you as soon as I can. We won’t stay longer than 2 hours.

3. Insistence (Stressed, hence no ‘ll contraction): He will do it, whatever you say. He will keep interrupting me.

4. Prediction (the similar meanings of other expressions for logical necessity and habitual present. The contracted form ‘ll is common):

- Specific Prediction: The game will be finished by now.

- Time Prediction: Oil will float on water.

- Habitual Prediction: He’ll (always) talk for hours if you give him the chance.

WOULD:

1. Willingness: Would you excuse me?

2. Insistence: It’s your own fault. You would take the baby with you

3. Characteristic activity in the past (often aspectual in effect): Every morning, he would go for a long walk (it was customary). John would make a mess of it (informal=it was typical).

4. Contingent use (in the main clause of a conditional sentence): He would smoke too much if I didn’t stop him.

5. Probability: That would be his mother.

MUST:

1. Obligation or Compulsion (in the present tense) (= be obliged to, have to – except in reported speech, only had to (not must) is used in the past) There are 2 negatives: (1) = not be obliged to: needn’t, don’t have to; (2) = be obliged not to: mustn’t.

- You must be back by 10 o’clock

2. Logical Necessity (Must is not used in sentences with negative or interrogative meanings (can being used instead). Must can occur in superficially interrogative but answer-assuming sentences.

- There must be a mistake (but there can not be a mistake)

- Mustn’t there be another reason for his behavior?

OUGHT TO:

Obligation; logical necessity or expectation: You ought to start at once. They ought to be here right now.

Note: Ought to and should both denote obligation and logical necessity, but are less categorical than must and have to. Ought to is often felt to be awkward in questions involving inversion, and should is preferred. Still less categorical than ought is had better/best (plus bare infinitive):

A: Must you go?

B: Well, I don’t have to. But I think I’d better (go).

THE MODALS and ASPECT:

The perfect and the progressive aspects are normally excluded when the modal expresses ‘ability’ or ‘permission’, and also when shall or will express ‘volition’. These aspect are freely used, however, with other modal meanings, e.g.:

Possibility: He may have missed the train. He may have been visiting his mother. He can’t be swimming all day.

Necessity: He can’t have been working. He must have left his umbrella on the bus.

Prediction: I must be dreaming. You must have been sitting in the sun. The guests will have arrived by now. John will still be reading his paper.

SEMI-MODALS: DARE, NEED, USED TO

DARE & NEED

When used as modals, they have the same meanings as when they are followed by a “to”-infinitive clause. However they are normally used as modals only in negative sentences and in questions:

Nobody dare disturb him.

How dare you speak to me like this?

Need you go so soon?

With his father, he need not fear.

Inflected forms: Unlike other modals, dare has some inflected forms which are occasionally used:

When it comes, she dare not express her feelings.

He dare not take his eyes off his assailant.

He dared not show he was pleased.

Use with other modals: Dare can be used with will, would, should and might:

Nobody will dare override what the towns decide.

I wouldn’t dare to go to Europe.

Use with ‘do’:

We don’t dare examine it. I didn’t dare speak or move.

USED TO:

- Has no inflected forms, and can not be used with other modals:

She used to get quit cross with her son.

- Can be used with ‘DO’ to say something happened regularly or existed in the past although it no longer happens or exists: They didn’t used to mind what we did.

- Is used to describe repeated actions in the past: I used to go to school on this road.

- Can describe past states and situations: Did you used to play with your train?

- Not common in negative structure. Instead, put ‘didn’t’ in front of it: Didn’t they used to mind?

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Social interactional uses of modals:

1. Making request:

Will/would/can/could you help me with this math problem?

2. Giving advice:

You should see a doctor.

Logical Probability uses of modals:

It could rain tomorrow --> It is possible that it will rain tomorrow.

Other uses of modals:

Ability: I can speak English.

Desire: She would like to travel around the world.

Offer: Would you like anything to drink?

Preference: He would rather study languages than mathematics.

Periphrastic modal counterparts:

Multiword forms ending in ‘to’, which function semantically much like true modals, are called periphrastic modals:

Modals Periphrastic Modals

Can -------------------------- be able to

Will -------------------------- be going to, be about to

Must ------------------------- have to, have got to

Should, Ought to ------------- be to, be supposed to

May ------------------------- be allowed to