Modal verbs to express ability

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
present past

We use can when we speak about general ability in the present:

Tommy can swim.
I can play the guitar. Can you play?

We use could when we speak about general ability in the past:

Picasso could paint when he was two.
I could swim before I could walk.
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.
Can you hear me? - Yes, I can.

Specific situations - was able to / could

We often use was able to when speaking about a specific situation:
We fixed the car and then we were able to drive home.

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.
They could smell smoke.
I could understand him perfectly.
Questions about ability - present

How many languages can you speak?
Can you name all the capitals of Europe?
Questions about ability - past

Could you write before you started school?
Could you ride a bike when you were small?

See also: Can, can’t, could, may: modal verbs for permission


Stuart is an English teacher and runs the Speakspeak website. He currently lives in Prague and has been teaching English for 20 years.