1 . -It ________Jack who is at the gate of the library.
-It ________him. I saw him off at the railway station just an hour ago.

A．can be; can't be	B．must be; can't be
C．can be; must have been	D．must be; can't have been

2 . It             be the vocabulary that caused you the problem in the exercise because you know a lot of words.

A．may	B．couldn’t
C．should	D．needn’t

3 . Some aspects of a pilot’s job ___ be boring and pilots often ___ work at inconvenient times．

A．can，have to	B．may，can
C．have to，may	D．ought to，must

4 . Judging from his accent, he_______ be from Australia.

A．needn't

B．mustn't

C．can't

D．wouldn't

5 . She is a quiet girl at school，but sometimes she _____ be very naughty.

A．should

B．would

C．can

D．will

6 . We hope that as many people as possible        join us for the picnic tomorrow.

A．need

B．can

C．must

D．should

7 . Helen________ go on the trip with us, but she isn’t quite sure yet.

A．shall

B．may

C．must

D．can

8 . 24. —Who______ it be that is knocking at the door?   
—It ______ be father, but I’m not sure.

A．can; must

B．can; may

C．must; can

D．may; must

9 . There is no light on--- they _______ be at home.

A．mustn’t

B．can’t

C．needn’t

D．shouldn’t