We use 'can' and 'could' to talk about a skill or ability.
; She can speak six languages.
; My grandfather could play golf very well
; I can't drive
can / can’t (for both general and specific ability)
; I can play the piano.
; She can speak English.
; He can’t drive – he’s too tired.
; We can’t come now.
could / couldn’t (for general ability)
; I could read when I was four.
; She could speak French when she was a child, but now she has forgotten it.
; He couldn’t dance at all until he took lessons.
; My grandfather couldn’t swim.
was able to / couldn’t (for specific ability)
; When the computer crashed yesterday, I was able to fix it.(not ‘I could fix it’)
; She was able to pass the exam, even though she hadn’t studied much.(not ‘she could
; He called us because he couldn’t find the house.
; I couldn’t open the window.
We can use verbs such as 'can', 'could' and 'may' to ask for and give permission. We also use modal verbs to say something is not allowed.
; Could I leave early today, please?
; You may not use the car tonight.
; Can we swim in the lake?