题目内容：

They must have stayed at home last night,_________?
A.haven't they
B.didn't they
C.mustn't they
D.needn't they
这个题应该选哪个呢!
题干有没有问题呢?

优质解答

选B
must have done sth.后面若有过去时间,如本题的“last night”,则反意疑问句用一般过去时形式：“didn't + 主语”