重点讲解

He can't have been ill.

He must have been tired.

It can't have been my new hat.

It must have been my old one.

She can't have been Danish.

She must have been Swedish.

He can't have been a dentist.

He must have been a doctor.

She can't have been forty.

She must have been fifty.

It can't have been the 20th.

It must have been the 21st.

He can't have been the youngest.

He must have been the oldest.

He can't have been reading.

He must have been sleeping.



Exercises

had to的后边只能跟动词的原形，must have been后可以跟形容词，名词和动词的-ing形式。

I must have been tired at that time.

He must have been a manager.

He must have been driving at 100 kilometers an hour.



1 must have been

2 had to

3 must have been

4 had to

5 had to

6 must have been



B Example

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.

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

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

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

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.