Can Could – We use can, could and may to ask for permission. We use can and may, but not could, to give permission. May is less common: Compare. asking for permission. formal/polite? giving permission. formal/polite? Can I ask you a question? informal. Yes, you can. Yes, you may. Yes, you could. informal. Could I use your phone? Practice can or could with your skypeclass Teacher.

Positive and negative forms:

The positive – can + base verb (infinitive without ‘to’):
She can swim even though she’s only four.
He can speak seven European languages.
They can sing really well.

The negative – cannot or can’t + base verb (infinitive without ‘to’):
She cannot tie her shoelaces yet.
He can’t speak Japanese.
They can’t whistle.

Present, past and future:

We use can in the present:
She can play the guitar but she can’t read music.
You can paint brilliantly.

We use could in the past:
He could play the piano well when he was young but he stopped practising and can only play it a little now.
She lived in Germany for five years so she could speak then but she’s forgotten it all now.

However, if we are talking about overcoming difficulty or about doing something in a specific situation we use was/were able to or managed to + base verb:
Alice said ‘I’ve managed to get somewhere to stay’.
He hadn’t done much revision but somehow he was able to pass the exam.

There is no future form of can. If we want to talk about abilities in the future, we use will be able to + base verb (infinitive without ‘to’):
After a few more lessons, I hope I’ll be able to make a perfect chocolate cake.
If you keep practising, you’ll be able to sing like a real professional soon.

However, we can use can in the future if we are deciding now about what to do in the future:
Can you pick up the kids after school on Friday?
A: Do you want to go to the cinema tomorrow?
B: OK. I can buy the tickets at lunch-time, if you like.

Conditional:

We use could in conditionals to mean would be able to:
She could come with us if she had a ticket.
You could become a manager if you had more sales experience.