can / can't for ability

We use can + the base form of a verb to say that someone has the ability to do something, or to ask for or give permission. The base form is the simple dictionary form of the verb with no -s, -ing, or -ed ending. One very important rule is that can never changes, no matter who the subject is: I can, you can, he can, she can, it can, we can, they can — there is no 'cans' or 'caning'. To make a negative, we use can't (or cannot in more formal writing). To ask about ability or permission, we put can before the subject: Can you swim? — Yes, I can. / No, I can't. Short answers always use can or can't, never the main verb. We use can for both ability (permanent or present skill) and permission (asking or allowing). For example: 'Sara can play the guitar really well, but she can't read music yet — can she take lessons, Mum?'