Grammar review The Modal Verbs (mv) can/could

Meaning

Forms of the MV

Forms of the infinitive

Kinds of sentences

Some other ways of expressing the same meaning

Sentence patterns

1. Ability, capability

can (can’t) – the Present Tense

could (couldn’t) – the Past Tense

Indefinite Infinitive

affirmative

interrogative

negative

to be able to, to know how to do smth, to have the ability to do smth.

He can perform complicated operations. He is a very skilful surgeon. Can she swim well? He could not feel or hear anything.

2. Possibility due to circumstances

can (can’t) – the Present Tense

could (couldn’t) – the Past Tense

Indefinite Infinitive

affirmative

interrogative

negative

to be able to, it’s possible to do smth

At a chemist’s shop you can get medicines of all kinds. I can go to the seaside this summer if I have enough money.

3.

a)Permission

b) Request

c)Prohibition

can – the Present Tense

could – the Past Tense in Reported Speech

can

could (a polite request)

can’t

Indefinite Infinitive

Indefinite Infinitive

Indefinite Infinitive

affirmative

interrogative

negative

to permit, to be allowed

The doctor said: “You can take long walks early in the morning”

Can (could) you give me some medicine for my headache?

You can’t visit him, he has an infectious disease.

4. Unreality

could – the Subjunctive II Form

The Indefinite Infinitive refers the action to the present or future.

The Perfect Infinitive indicates the action which was not carried out in the past

affirmative

interrogative

negative

would be able to do smth;

would have been able to do smth

Why don’t you want the doctor to come? He could prescribe some medicine to bring down the fever (if he came).

You could have stayed in bed for a few days. But you didn’t.

5. Uncertainty, doubt, astonishment

can/could

The Indefinite Infinitive refers the action to the present or future.

The Continuous Infinitive refers the action to the present.

The Perfect Infinitive refers the action to the past.

The Perfect Continuous Infinitive denotes an action begun in the past and continued into the moment of speaking

interrogative (general questions)

Is it possible that … ?

Do you believe that …?

Can (could) he be her husband?

He is twice as old as she is.

Can (could) she still be running a high temperature?

Can (could) he have been operated on?

Can (could) they have been keeping to a diet for a few years?

6. Incredulity, improbability

can’t/

couldn’t

Indefinite Infinitive

Continuous Infinitive

Perfect Infinitive

Perfect Continuous Infinitive

negative

It’s hardly possible that; I refuse to believe that; I don’t think it’s possible that; it’s next to impossible that; I don’t believe that; I doubt that; It’s incredible (doubtful) that

He can’t (couldn’t) be her husband.

She can’t (couldn’t) be still running a high temperature.

He can’t (couldn’t) have been operated on.

They can’t (couldn’t) have been keeping to a diet for a few years.

7. For emotional colouring

can/could (in present time contexts)

Indefinite Infinitive

Continuous Infinitive

Perfect Infinitive

Perfect Continuous Infinitive

interrogative

(special questions)

What can (could) you know of such things?

What can (could) they be speaking about?

How can (could) you have made such a mistake?

What can (could) he have been doing all this time?