英语选择题（情态动词）
问题描述：
英语选择题（情态动词）
——Look ,the light in the teacher's office is still on .Mr.Brown is working there .He always works late at night.—— It ___be Mr.Brown .He's gone to Hawaii on vacation.
A.can't B.mustn't C.may D.must
,为什么?
答
A 因为后边的句子说明他已经去夏威夷度假了.所以肯定不是布朗先生.
must 只能表示肯定推测,否定推测肯定不应该是can't .因为mustn't 表示禁止.