1 . —The telephone line to the headmaster is always busy.
—Someone ______ the telephone.

A．need use

B．should use

C．must be using

D．must use

2 . Carol knows a lot about reality shows. She ________ have seen such programs frequently.

A．can

B．would

C．will

D．must

3 . ---Where's John?
---He ________ be drinking coffee in the sitting room as usual.

A．must

B．need

C．should

D．might

4 . __ It is so late. Our son __________ be back .
__ Don’t   worry . I dare say he ________ have some extra work to do.

A．can ; must

B．will ; might

C．should ; must

D．must ; may

5 . ．—What’s the matter with the man hanging his head there?
—Well, if you _______ know, he was caught stealing my bike.

A．must

B．may

C．can

D．shall