Can

from English Grammar Today

 

Can: forms

Affirmative (+) form

Can comes first in the verb phrase (after the subject and before another verb):

We [verb phrase]can take the train to Birmingham.

Can is never used with another modal verb:

He can hear the music from his room sometimes.

Not: He can might hear the music … or He might can might hear the music …

Negative (−) form

The negative form of can is can’t. We don’t use don’t/doesn’t/didn’t with can:

I can’t believe you said that!

Not: I don’t can believe you said that!

We can use the full form cannot (one word) in formal contexts or when we want to emphasise something:

I cannot understand why she behaves like that.

See also:

• Modality: forms

Question (?) form

Warning:

The subject and can change position to form questions. We don’t use do/does/did:

Can this really be true?

Not: Does this can really be true?

Can’t you ask for another day off work?

We use can and can’t in question tags:

You can’t take photos inside the museum, can you?

Abby can speak Japanese, can’t she?

 

Can: uses

Permission

We often use can to ask for or give permission:

Can I take Daisy for a walk?

Students can use calculators during the exam.

We use can’t to forbid (say what you must not do):

You can’t park there.

You can’t just take the day off work. You have to have permission in advance.

See also:

• May

Ability

We often use can to talk about ability to do something in the present or future:

I can sing one song in Polish.

Can you sleep on your back?

We can go swimming after school tomorrow, if you like.

We often use can with verbs of perception such as hear, see, smell, taste, and mental process verbs such as guess, imagine, picture, understand and follow (in the sense of ‘understand’):

I can hear you.

I can see her coming down the road now.

Can you smell something burning?

I can guess why you’re angry.

We can’t follow these instructions for installing this new DVD player. (We can’t understand these instructions.)

General truths

We use can to talk about things which we think are usually, but not always, true:

Reducing cholesterol through diet can be difficult. (It’s not always difficult for everyone, but in general it is difficult.)

Fireworks can frighten pets.

Swans can be very vicious.

We don’t normally use could to talk about what we believe to be true in the present.