Can x Could x Be able to

[Emanuelli]

Hello and have a nice Sunday!

Could you help me understand the use of can/could and be able to better?

I was reading a textbook where I found out a small difference.

Thank you very much.

[Tdol]

Can- present ability/ Could past ability
For possibilty, can is a stronger possibility.

The general distinction between can/could and be able to is the occasion:

I could swim when I was five / I wasn't able to swim yesterday because I was ill.

However, this distinction is far from a rule.