()4.—Look! The man looks like Mr Li.
—It be him because he has been in Canada for a week.

A.can't
B.needn't
C.mustn't
D.shouldn't

4. A

()5.The successful launch of Shenzhou-20 be the result of many people's hard work.

A.must
B.can
C.should
D.need

5. A

Ⅱ. 选词填空(必要时可变否定)
must, can, may
6. Flying is the fastest way of travelling, but you wait for hours at the airport.
7. The apple pie be Daniel's. I saw him order one just now.
8. Jane be in the classroom now. She has gone to the teachers' office.
9. Jack be at home because I saw him in the library just now.
10. After running such a long way in the marathon, you feel very tired.

6. may 7. must 8. can't 9. can't 10. must

Ⅲ. 根据短文内容,用 must, may, might, could 或 can't 填空
[情境题] Sherlock Holmes and Dr Watson were having a cup of tea at five, as they usually did, when the doorbell rang.
“That 11. be Mrs Brown. I am expecting her this evening,” said Sherlock Holmes.
“No, it 12. be her. She called this morning while you were out to say she would not be able to make it this evening. She also said she 13. come tomorrow evening, but she would call again anyway to confirm it,” replied Dr Watson.
“Well, that's very strange, my dear Watson. Mrs Brown 14. have called this morning because I was with her all the time till we parted for lunch. It 15. have been someone else pretending(假装) it was her,” said Sherlock Holmes.
“But why? Do you think something 16. have happened to the real Mrs Brown?” replied Dr Watson in a fearful tone(语气).
The doorbell rang again.
“Well, my dear Watson, the answer 17. be waiting at the door right now. You'd better go and see, but I'm afraid it is the person who called this morning. So be careful,” said Sherlock Holmes.
Dr Watson hurried towards the door...

11. must 12. can't 13. might/could 14. can't 15. must 16. might/may/could
17. might/may/could