--The windows must have taken you quite a long time that day.Right. They for m

问题补充：

----- The windows must have taken you quite a long time that day.

----- Right. They for months.

A. haven’t been cleaned

B. didn’t clean

C. hadn’t been cleaned

D. haven’t cleaned

答案：

A. haven’t been cleaned

B. didn’t clean

(答案→)C. hadn’t been cleaned

D. haven’t cleaned

解析：考查时态。根据must have taken可知是过去的某个时间擦窗户的，那么窗户很久没有被擦是在这之前，所以使用过去完成时。句意：—那些窗户一定花了你很长时间吧！—是的。他们已经好几个月没有被擦了。