如果想描述一個人有做一件事情的能力（ability），就可以使用固定搭配 “able to” 或情態動詞 “can”；如果想描述一個人不具備做一件事情的能力，那么則應該用 “unable to” 或 “can’t”。情態動詞 “could” 和它的否定形式 “couldn’t” 可分別用來談論一個人在過去是否具有做一件事情的能力。此外，情態動詞 “can、could” 和 “might” 都可以用來描述一件事發生的可能性（possibility）。

做八道題，考一考自己能否正確使用表示能力和可能性的情態動詞。

1. He’s lived in Russia. He _______ speak Russian fluently.

a) can

b) mustn’t

c) will have to

d) is better

2. Jimi Hendrix was so talented, he _______ play the guitar with his teeth!

a) may

b) should

c) could

d) will

3. I don’t think _______ travel to Mars for a long time.

a) we have to

b) we should have to

c) we must

d) we’ll be able to

4. Which of the following sentences expresses possibility?

a) That noise must be the protesters marching through the streets.

b) She might have stolen the money – she knew where I kept it.

c) You don’t look very well, you should see a doctor.

d) You don’t have to submit your essay until the 2nd of March.

5. The trains aren’t running normally, so there _______ a problem getting to the match on Saturday.

a) could be

b) can’t be

c) can be

d) should be

6. She didn’t have a driving license then, so she _______ drive a car.

a) mustn’t

b) can’t

c) couldn’t

d) shouldn’t

7. I’m really sorry, but I _______ come to dinner on Tuesday, I’ve got too much work to do.

a) wouldn’t

b) couldn’t

c) shouldn’t

d) won’t be able to

8. Which of the following sentences expresses ability?

a) Students should wear uniforms to school at all times.

b) You can’t learn how to ballet dance without going to ballet classes.

c) Where is everyone? They should be here by now!

d) You might find that shirt you want from this shop.

答案

1) a, 2) c, 3) d, 4) b, 5) a, 6) c, 7) d, 8) b.