Couldn´t / Must

Match the sentences.

1. I tried to phone you but there was no answer.

a) I must have been asleep.
b) I couldn't have been asleep.

2. I tried to phone you but there was no answer.

a) I must have been in the office.
b) I couldn't have been in the office.

3. I passed Jane in the street and she didn't speak to me.

a) She must have seen you.
b) She couldn't have seen you.

4. I've rung their office three times and have had no reply.

a) They must have all gone home.
b) They couldn't have all gone home.

5. I'm sure that Harry was sacked for stealing.

a) Not Harry! He must have done something so awful.
b) Not Harry! He couldn't have done something so awful.

6. That suit looks fantastic.

a) You must have paid a lot for it.
b) You couldn't have paid a lot for it.

7. I can't find my wallet.

a) I must have left it in the restaurant.
b) I couldn't have left it in the restaurant.

8. We went to an excellent restaurant but John hardly ate a thing.

a) He must have been hungry.
b) He couldn't have been hungry.

9. You didn't do what I told you to do.

a) You must have been listening.
b) You cannot have been listening.

10. Thank you for all your help.

a) I must have done it without you.
b) I couldn't have done it without you.