问题
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.
A:must; can’t
B:must; mustn’t
C:can’t; can’t
D:can’t; mustnit;
B:must; mustn’t
C:can’t; can’t
D:can’t; mustnit;
正确答案是：
