This verb only has 2 forms: a present form can, and a past and conditional form, could. The verb that follows it is in the infinitive without ‘to’:

Examples:
I can ride a bicycle.
I could swim when I was four.

In other tenses, we use be able to.

🔖PRESENT TENSE

Affirmative:

  • I can
  • You can
  • He can
  • She can
  • It can
  • We can
  • You can
  • They can
Example: I can speak English.


Negative:

  • I cannot/can’t
  • You cannot/can’t
  • He cannot/can’t
  • She cannot/can’t
  • It cannot/can’t
  • We cannot/can’t
  • You cannot/can’t
  • They cannot/can’t
Example: I can’t swim.


Interrogative:

  • Can I?
  • Can you?
  • Can he?
  • Can she?
  • Can it?
  • Can we?
  • Can you?
  • Can they?
Example: Can you drive?


🔖PAST AND CONDITIONAL TENSES

Affirmative:

  • I could
  • You could
  • He could
  • She could
  • It could
  • We could
  • You could
  • They could
Example: I could read when I was six.


Negative:

  • I couldn’t
  • You couldn’t
  • He couldn’t
  • She couldn’t
  • It couldn’t
  • We couldn’t
  • You couldn’t
  • They couldn’t
Example: I couldn’t play tennis yesterday.


Interrogative:

  • Could I?
  • Could you?
  • Could he?
  • Could she?
  • Could it?
  • Could we?
  • Could you?
  • Could they?
Example: Could you go swimming on Sunday?


🔖FUTURE TENSE

We use will be able to:
Example: Sorry, but I don’t think I’ll be able to come to your party.


🔖PAST PARTICIPLE

We use been able to:
Example: Margaret is ill. She hasn’t been able to finish her homework.