There is no light in the room. They must have gone to the lecture.?A. didn’t theyB. haven’

问题补充：

There is no light in the room. They must have gone to the lecture.?

A. didn’t they

B. haven’t they

C. don’t they

D. mustn’t they

答案：

A. didn’t they

(答案→)B. haven’t they

C. don’t they

D. mustn’t they

解析： 本题是一个反义疑问句，前句是肯定的句子，后句应该用否定的结构+人称，前句的助动词是have，故用其否定形式haven’t，故本题选B。