Modal Verbs for Ability

We can use modal verbs to talk about ability (either general ability or specific ability in a particular situation). The modal verbs of ability are ‘can’, ‘could’, and ‘be able to’. Ability can be expressed in the past, present, or future.

Ability in the present

‘Can‘ is a modal verb that describes what someone is able to do, i.e. general ability in the present. It is used in different forms to describe past and present abilities.

• Peter can cook Italian food.

Positive statements

In positive statements we put ‘can‘ between the subject and the main verb in its base form:

subject + can + the verb (infinitive without ‘to’)

• I can ride a bicycle.
• They can help you with building your house.

Negative statements

The negative form of ‘can‘ becomes ‘can not’ or contracted ‘cannot’ (‘can’t’):

• Jeffrey cannot play the piano.
• She can’t go with us because she’s sick.

Questions

Questions with ‘can‘ are formed by swapping the subject and the modal verb:

Can + subject + the verb (infinitive without ‘to’)

• Can Jane play tennis?
• Can he drive a car?

Ability in the past

Could

To talk about ability in the past we use ‘could‘, which is the past form of ‘can‘.

• I can’t dance rumba now (present ability), but I could when I was younger (past ability).
• I could read when I was four.

The negative form of ‘could‘ is ‘could not (couldn’t)’. ‘Couldn’t‘ can be used to describe general and specific ability in the past:

• I couldn’t go to that restaurant because it was too expensive. (general ability)
• My grandfather couldn’t swim. (general ability)
• He called us because he couldn’t find the house. (specific ability)
• I couldn’t open the window. (specific ability)

Was able to

To talk about for specific ability in a particular situation in the past we can also use ‘was able to‘. The negative form of ‘was able to‘ is ‘wasn’t able to’ or ‘was unable to‘.

• 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 pass’)

Could have + Past Participle

To talk about an ability someone had in the past, but didn’t use, we can use ‘could have + Past Participle‘:

• I could have passed the test well but I didn’t practise enough.
• He could have come earlier.

Ability in the future

We don’t use ‘can‘ to describe general ability in the future. Instead, we use ‘will be able to’:

• Peter can play the accordion quite well (present ability). In a year or two he will be able to give concerts (future ability).
• Next Sunday I will be able to see the new fountains in the park.

Negative statements about future ability are formed using ‘won’t be able to’ or ‘will be unable to’:

• If you don’t study well, you won’t be able to find a good job.
• Sorry, I’ll be unable to call him at 2 PM. I’ll be in a meeting at that time.

BUT sometimes we can use ‘can‘ to describe a specific future ability:

• I can help you tomorrow.
• I can’t come to the party.

Watch this video from mmmEnglish to see how the modal verbs of ability are used:

See also:

Modal Verbs: Overview

Modal Verbs for Possibility

Modal Verbs for Deduction