Listen!Someone is singing in next room.() it be Mary?
NO.It ( ) be her.She is at school now.

A.will , may not
B.must mustn't
C.can can't
D.may mustn't

答案：C

译文：听!有人在隔壁唱歌,是玛丽吗?

那不可能是玛丽,她现在在学校呢!

解析：can 表疑问推测

can't 表否定推测