needn't have done和didn't need to do 的不同:
1、needn't have done 表示 本不需要做某事,但是已经做了
2、didn't need to do 表示 (过去)没有必要做某事,但是到底做没做某事,应该根据语境来分析。
一、needn't have done
1、这里的 need 是个
情态动词。
2、needn't have done 源自于 need have done。Need have done 这个结构主要用于否定句和
疑问句,一般不用于肯定句:
①用于否定句时,变为本问题中的needn't have done,表示本来不必做某事,但是实际上却做了;
②用于疑问句时,表示询问某一过去动作的必要性。
二、didn't need to do
1、这里的 need 是个
实义动词。
2、didn't need to do 源自于 need to do(需要做某事)。Didn't 是
过去式,表否定,所以didn't need to do 表示(过去)没有必要做某事。
※虽然 didn't need to do 表示(过去)没必要做某事,但是到底做没做,得根据语境判断:例如
① You didn't need to give me any more money, but thank you. 这句话来看,说话的人本不需要别人给他钱了,但是通过 "thank you" 可以看出,别人还是给了说话人钱。
② I didn't need to go to school because of my illness, so I stayed at home. 这句话来看,主语 I (我)因为生病没必要去学校,从“stayed at home”可以看出,I(我)也确实没去学校。