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UNIT 25 Can, could, and be able to
a. We use can (do) to say that something is possible or that someone has the ability to do something. The negative is can’t. You can see the ocean from our bedroom window.
Can you speak any foreign languages?
I’m afraid I can’t come to your party next Friday.
Be able to is possible instead of can, but can is more usual:
Are you able to speak any foreign languages?
But can has only two forms: can (present) and could (past). So sometimes you have to use be able to:
I haven’t been able to sleep recently. (can has no present perfect)
Sue might not be able to come tomorrow. (can has no infinitive)
I’m very busy today, but I should he able to meet with you tomorrow.
b. Could and was able to Sometimes could is the past of can. We use could especially with these verbs:
see hear smell taste feel remember understand
When we went into the house, we could smell something burning.
She spoke in a low voice, but I could understand what she was saying.
We also use could to say that someone had the general ability to do something:
My grandfather could speak five languages.
When Joe was 16, he could run 100 meters in 11 seconds.
But if you mean that someone managed to do something in one particular situation, you have to use was/were able to (not could): The fire spread through the building very quickly, but everyone was able (= managed) to escape. (not could escape)
They didn’t want to come with us at first, but finally we were able (= managed) to persuade them. (not could persuade)
Compare could and was able to in this example:
Jack was an excellent tennis player. He could beat anybody. (= He had the ability to beat anybody.)
But once he had a difficult game against Bob. Bob played very well, but in the end Jack was able to beat him. (= He managed to beat him in this particular game.)
The negative couldn’t is possible in all situations:
My grandfather couldn’t swim.
We tried hard but we couldn’t persuade them to come with us.
For can see also Unit 30. For could see also Unit 26 and 30.
UNIT 25 Exercises
25.1 Use can or be able to. Sometime it is possible to use either; sometimes only be able to is possible.
Examples: George has traveled a lot. He can (or is able to) speak four languages.
I haven’t been able to sleep very well lately.
1. Tom ________________________ drive, but he doesn’t have a car.
2. I can’t understand Martin. I’ve never ________________________ understand him.
3. I used to ________________________ stand on my head, but I can’t do it now.
4. Ask Ann about your problem. She should ________________________ help you.
25.2 Complete the sentence with could …
Example: I can’t sing now, but I could sing very well when I was a child.
1. He can’t play tennis very well now, but he ________________ fairly well when he was younger.
2. She can’t run very fast now, but when she was in school she __________ faster than anyone else.
3. I can’t swim very far these days, but ten years ago I ________________________ from one side of the lake to the other.
25.3 Answer the questions with was/were able to.
Example: Did you persuade them?
Yes. It was difficult, but we were able to persuade them.
1. Did they find your house?
Yes. It took them a long time, but they ________________________
2. Did you win the match?
Yes. It wasn’t easy, but I ________________________
3. Did the thief escape?
Yes. The police officer chased the thief, but he ________________________
25.4 Complete each sentence with could, was/were able to, or couldn’t.
Examples: My grandfather was very clever. He could (or was able to) speak five languages.
I looked everywhere for the book, but I couldn’t find it.
The fire spread quickly, but everyone was able to escape.
1. He had hurt his leg, so he ________________________ walk very well.
2. She wasn’t at home when I called, but I ________________________ contact her at her office.
3. I looked very carefully, and I ________________________ see a figure in the distance.
4. They didn’t have any tomatoes in the first store I went to, but I ______ get some in the next store.
5. My grandmother loved music. She ________________________ play the piano very well.
6. The boy fell into the river, but fortunately we ________________________ rescue him. |
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