Ability
Level: beginner
We use can and can't to talk
about someone's skill
or general abilities:
She can speak several languages.
He can swim like a fish.
They can't dance very well.
We use can and can't to talk
about the ability to do something
at a specific time in the
present or future:
I can see you.
Help! I can't breathe.
We use could and couldn't
to talk about the past:
She could speak several languages.
I couldn't see you.
Level: intermediate
We use could have to say that
someone had the ability
or opportunity
to do something, but did not do it:
I could have danced all night.
[but I didn’t]
She could have learned Swahili,
but she didn't want to.