Can vs. Be Able To


Be able to often has the same meaning as can.

  • I am unable to/can’t understand his motive.
  • He is able to/can support her.

Can is preferred in expression like can see, can hear etc. It is also used in the sense of know how to?

  • I can knit. (More natural than I am able to knit.) (= I know how to knit.)
  • I can see a ship. (More natural than I am able to see a ship.)

Be able to is preferred in cases, where can/could is not grammatically possible.

  • I might be able to help you. (NOT I might can help you.)
  • Someday scientists will be able to find a cure for cancer. (NOT Someday scientists will can find —)
Be able to often has the same meaning as can. In some cases, they are both possible.

Can vs. Be able to | English Grammar Worksheet

Complete the following sentences using can or be able to.

1. I —————– read this.

a) can’t
b) am unable to
c) Either could be used here

2. Some people ——————— stand on their head.

a) can
b) are able to
c) Either could be used here

3. I am ———————- understand his motives.

a) can’t
b) unable to
c) Either could be used here

4. ——————– you play the piano?

a) Can
b) Are you able to
c) Either could be used here

5. One day human beings will ——————– colonize Mars.

a) can
b) be able to
c) Either could be used here

6. What have you ——————— find out?

a) been able to
b) could
c) can

7. She should ——————- go.

a) be able to
b) can
c) could

8. I might —————– help.

a) be able to
b) can
c) could

Answers

1. I can’t read this. / I am unable to read this.

2. Some people can stand on their head. / Some people are able to stand on their head.

3. I am unable to understand his motives.

4. Can you play the piano?

5. One day human beings will be able to colonize Mars.

6. What have you been able to find out?

7. She should be able to go.

8. I might be able to help.