A

1 He must have been ill.

2 He had to stay at home.

3 She must have been German.

4 I lost my pen so I had to buy a new one.

5 He forgot his case so he had to return home.

6 She must have been sleeping.

B

1 I don't think they were. They can't have been Canadian. They must have been Australian.

2 I don't think she was, She can't have been Finnish. She must have been Russian.

3 I don't think they were. They can't have been Japanese. They must have been Chinese.

4 I don't think they were. They can't have been butchers. They must have been bakers.

5 I don't think she was. She can't have been a dentist. She must have been a doctor.

6 I don't think he was. He can't have been a sales rep. He must have been the boss.

7 I don't think she was. She can't have been seventeen. She must have been twenty-one.

8 I don't think they were. They can't have been five. They must have been seven.

9 I don't think he was. He can't have been seventy-six. He must have been over eighty.

10 I don't think she was. She can't have been fifty-five. She must have been under fifty.

11 I don't think it was. It can't have been the 17th yesterday. It must have been the l6th yesterday.

12 I don't think it was. It can't have been Tuesday yesterday. It must have been Wednesday yesterday.

13 I don't think it was. It can't have been the 19th yesterday. It must have been the 20th yesterday.

14 I don't think it was. It can't have been cheap. It must have been expensive.

15 I don't think it was. It can't have been easy. It must have been difficult.

16 I don't think she was. She c an't have been old. She must have been young.

17 I don't think he was. He can't have been ill. He must have been tired.

18 I don't think they were. They Can't have been listening to the radio. They must have been Watching television.

19 I don't think she was. She can't have been retiring. She must have been looking for a new job.20 I don't think they were. They can't have been sitting. They must have been standing.