---- Someone is knocking at the door.---- It _____

试题详情及答案解析

---- Someone is knocking at the door.
---- It ______ be Tom. He is still in the school.

A．can’t	B．mustn’t
C．could not	D．might; not

答案：A

试题分析：句意：--有人在敲门。--不是汤姆，他还在学校。根据He is still in the school.可知肯定不是汤姆在敲门，否定猜测用can’t，故选A
考点：考查情态动词表推测的用法。