I can swim.
Can is a modal verb and so always has the same form:

I can
You can

We can
You can

He can
She can
It can

They can

After can we use the base form of the verb.


can swim.
She can speak Spanish.

The negative form of can is can’t.

We use can to talk about ability and permission.

  • Ability
They can drive.
She can’t use a computer.
  • Permission
He can’t go to the party.
They can park there.

As with all modal verbs, to make a question with can we invert can and the subject:

You can swim. (affirmation)
Can you swim? (question)

He can speak German. (affirmation)
Can he speak German? (question)