同学你好，该知识点来自沪江网校《2020考研名师刷押联报班【政治】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
A
1 He must have been ill.
2 He had to stay at home. 表示过去必须做某事，用had to
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.

祝同学学习进步~