— There’s somebody at the door. Who ______ it be? Is it the postman ?
—No, it ______ be him. It’s just seven o’clock. It’s too early.

A．may, can’t

B．will, won’t

C．may, mustn’t

D．must, may not

科目 英语   题型 单选题   难度 较难

知识点： 情态动词的被动语态