It was very kind of you to clean the office, though you___

题目

It was very kind of you to clean the office, though you___
A needn't do B wouldn't have C didn't have to D mustn't have done 选哪个,为什么现那个.谢谢

答案

选c 句子意思是,你人真好啊帮忙打扫办公室,尽管你不用必须去做.