1 . There’s a public sign in the library, saying no person ________ bring food and drinks into the reading room.

A．shall

B．will

C．need

D．must

2 . —Can I please have a little more time?
—No, you_________. The test time is up.

A．can’t

B．couldn’t

C．mustn’t

D．needn’t

3 . —— I can’t get through to the general manager’s office anyhow.
—— The line is busy. Someone _____ the telephone.

A．must use

B．uses

C．must have been using

D．must be using