题干
---Look. The man at the gate _____ be our headmaster. He is always standing there every morning.
---No. it ____ be him. He is having a meeting in the office now.
---No. it ____ be him. He is having a meeting in the office now.
A：must; can’t
B：must; mustn’t
C：can’t; can’t
D：can’t; mustn’t
答案(点此获取答案解析）
A
