Can, could and be able to 📕

Can: ability now

I can speak three languages.

She can't swim.

Can you drive?

Can: permission

You can park here.

Can I use your phone?

Could: ability in the past

When I was young, I could run very fast.

I couldn't sleep last night.

Could: polite requests

Could is more polite than can:

Could you open the window, please?

Be able to: in other tenses

Can has no future form and no -ing form. Use be able to instead.

I will be able to help you tomorrow.

I haven't been able to call her.

I'd like to be able to speak English well.

✗ I will can help you.

✓ I will be able to help you.