问题
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:must, may not
B:will, won’t
C:may, mustn’t
D:may, can’t
B:will, won’t
C:may, mustn’t
D:may, can’t
正确答案是：
