It was very kind of you to do the washing up, but you it.
A. mustn't have done
B. wouldn't have done
C. mightn't have done
D. didn't have to do
网友回答
A. mustn't have done
B. wouldn't have done
C. mightn't have done
(答案→)D. didn't have to do
解析：考查情态动词和虚拟语气的用法。don't have to do sth.“不必做某事”。也可以说needn't have done it。