The key answer of exercise 1

a)

1. c
2. b
3. f
4. h
5. d
6. a
7. e
8. g

b)

1. must have been
2. might have gone
3. can’t have seen
4. might not have heard
5. can’t have moved
6. might have fallen
7. must have done
8. might not have read

c)

1. I shouldn't have shouted at him.
2. We should have filled up at the last garage.
3. He oughtn’t have left it on his desk.
4. You shouldn’t have bought such high heels.
5. I oughtn’t have stayed up to watch that horror film.
6. They ought to have dressed up for the wedding.
7. It should have gone off at 7.30.
8. She should have taken a taxi to the station.