English Grammar in Use With Answers » Unit 27: Could (do) and could have (done)

We use could in a number of ways. Sometimes could is the past of can (see Unit 26):
  • Listen. I can hear something. (now)
  • I listened. I could hear something. (past)

But could is not only used in this way. We also use could to talk about possible actions now or in the future (especially to make suggestions). For example:
  • A: What shall we do tonight?
    B: We could go to the cinema .
  • A: When you go to Paris next month, you could stay with Sarah.
    B: Yes, I suppose I could.

Can is also possible in these sentences ('We can go to the cinema.' etc.). Could is less sure than can.

We also use could (not can) for actions that are not realistic. For example:
  • I'm so tired, I could sleep for a week. (not I can sleep for a week)

Compare can and could:
  • I can stay with Sarah when I go to Paris. (realistic)
  • Maybe I could stay with Sarah when I go to Paris. (possible, but less sure)
  • This is a wonderful place. I could stay here for ever. (unrealistic)

We also use could (not can) to say that something (a situation or a happening) is possible now or in the future. The meaning is similar to might or may (see Unit 29):
  • The story could be true, but I don't think it is. (not can be true)
  • I don't know what time Lisa is coming. She could get here at any time.

Compare can and could:
  • The weather can change very quickly in the mountains. (in general)
  • The weather is nice now, but it could change. (the weather now, not in general)

We use could have (done) to talk about the past. Compare:
  • I'm so tired, I could sleep for a week. (now)
    I was so tired, I could have slept for a week. (past)
  • The situation is bad, but it could be worse. (now)
    The situation was bad, but it could have been worse. (past)

Something could have happened = it was possible but did not happen:
  • Why did you stay at a hotel when you were in Paris? You could have stayed with Sarah. (you didn't stay with her)
  • David was lucky. He could have hurt himself when he fell, but he's OK.

We use couldn't to say that something would not be possible:
  • I couldn't live in a big city. I'd hate it. (= it wouldn't be possible for me)
  • Everything is fine right now. Things couldn't be better.

For the past we use couldn't have (done):
  • We had a really good holiday. It couldn't have been better.
  • The trip was cancelled last week. Paul couldn't have gone anyway because he was ill. (= it would not have been possible for him to go)

27.1 Answer the questions with a suggestion. Use could.

  1. Where shall we go for our holidays?
    (to Scotland) .
  2. What shall we have for dinner tonight?
    (fish) We __________ .
  3. When shall I phone Vicky?
    (now) You __________ .
  4. What shall I give Ann for her birthday?
    (a book) __________ .
  5. Where shall we hang this picture?
    (in the kitchen) __________ .

27.2 In some of these sentences, you need could (not can). Change the sentences where necessary.

  1. The story can be true but I don't think it is.
  2. It's a nice day. We can go for a walk.
    __________ .
  3. I'm so angry with him. I can kill him!
    __________ .
  4. If you're hungry, we can have dinner now.
    __________ .
  5. It's so nice here. I can stay here all day, but unfortunately I have to go.
    __________
  6. A: Where's my bag. Have you seen it?
    B: No, but it can be in the car.
    __________
  7. Peter is a keen musician. He plays the flute and he can also play the piano.
    __________
  8. A: I need to borrow a camera.
    B: You can borrow mine.
    __________
  9. Be careful climbing that tree. You can fall.
    __________

27.3 Complete the sentences. Use could or could have + a suitable verb.

  1. A: What shall we do this evening?
    B: I don't mind. We to the cinema.
  2. A: I spent a very boring evening at home yesterday.
    B: Why did you stay at home? You __________ out with us.
  3. A: Have you seen this job advertised in the paper? You __________ for it.
    B: What sort of job? Show me the advertisement.
  4. A: How was your exam? Was it difficult?
    B: It wasn't so bad. It __________ worse.
  5. A: I got very wet walking home in the rain last night.
    B: Why did you walk? You __________ a taxi.
  6. A: Where shall we meet tomorrow?
    B: Well, I __________ to your house if you like.

27.4 Complete the sentences. Use couldn't or couldn't have + these verbs (in the correct form):

  • be
  • be
  • come
  • find
  • get
  • live
  • wear
  1. I in a big city. I'd hate it.
  2. We had a really good holiday. It better.
  3. I __________ that hat. I'd look silly and people would laugh at me.
  4. We managed to find the restaurant you recommended, but we __________ it without the map that you drew for us.
  5. Paul has to get up at 4 o'clock every morning. I don't know how he does it. I __________ up at that time every day.
  6. The staff at the hotel were really nice when we stayed there last summer. They __________ more helpful.
  7. A: I tried to phone you last week. We had a party and I wanted to invite you.
    B: That was nice of you, but I __________ anyway. I was away all last week.

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