Modal auxiliary verb can

Posted by Manjusha. Filed in English Grammar

Can is a modal auxiliary verb. It is followed by an infinitive without to. There is no -s in the third person singular.

Questions and negatives are made without do.


Can is used to talk about ability and possibility, to ask for and give permission, and to make requests and offers.

To talk about theoretical possibility

We can use can to talk about theoretical possibility - to say that situations and events are possible theoretically.

Note that we do not use can to talk about future probability - to say that something will happen in future. We express this idea with may or might.

Note that might expresses a less definite possibility than may. Could is also used in the same sense.

To talk about logical possibility

Can is often used in questions and negatives to talk about the logical possibility that something is true.

With this meaning can is not possible in affirmative clauses. Instead, we use could, may or might.

To talk about ability

We can use can to talk about present or general ability - to say that we are capable of doing something.

Note that be able to can often be used with similar meanings.

Cannot (also can’t) shows inability.

We do not use can to talk about future ability. Instead, we use will be able to or other words.

To ask for or give permission

Can is sometimes used to ask for and give permission. Some people, however, think that may is more correct than can.

Note that we can also use could to ask for permission. It is a more polite form of can .

Cannot is used to refuse permission.

To make requests and offers

Can is used in polite requests and offers of help.

Note that Could is a more polite way of making requests and offers.

Sections in this article

Expressions without prepositions
Prepositions at the end of clauses
Prepositions: some useful points
Common prepositions: usage