We use the modal verbs can, could and be able to + verb infinitive to talk about ability.
Here’s an overview, with examples:
|Modal verbs to express ability|
We use can when we speak about general ability in the present:
Tommy can swim.
We use could when we speak about general ability in the past:
Picasso could paint when he was two.
|The negative of can is can’t (cannot):
I can’t ski and I can’t skate.
|The negative of could is couldn’t (could not):
I couldn’t swim until I was ten.
|Specific situations – can
We also use can to speak about specific situations in the present:
I can hear you but I can’t see you.
|Specific situations – was able to / could
We often use was able to when speaking about a specific situation:
However, we prefer could to speak about a specific situation in the past when we use these verbs: see, hear, feel, smell, taste, remember, believe, understand, decide.
|Questions about ability – present
How many languages can you speak?
|Questions about ability – past
Could you write before you started school?