Look! The man at the gate ________ be our headmaster．He is always standing there every morning．

1. A.
   must
2. B.
   mustn’t
3. C.
   can
4. D.
   can’t

——Look! The man at the gate       be our headmaster．He is always standing there every morning．

——No, it       be him．He is holding meeting in the office now．

A．must, can’t            B．must, mustn’t       C．can, can’t             D．can, mustn’t

—Look! The man at the gate ______ be our headmaster. He is always standing there every morning.
—No, it ______be him. He is holding a meeting in the office now.