----- 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
网友回答
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。