问题描述：
--Catharine,I have cleaned the room for you.--- Thanks.You ________ it.I could manage it myself
.A needn’t do B.needn’t have done
C.mustn’t do D.shouldn’t have done
为何不选A
.A needn’t do B.needn’t have done
C.mustn’t do D.shouldn’t have done
为何不选A
问题解答：
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