牛津实用英语语法:153 needn't have（done）和did't have done

　　A neednt have done意指没必要干某件事但多余地干了，即浪费了时间：

　　You neednt have watered the flowers，for it is going to rain.

　　你本不必浇那些花，因为就要下雨了。(你浪费了时间。)

　　You neednt have written such a long essay.The teacher only asked for

　　300 words，and you have written 600.

　　你本不必写这么长的文章。老师只要求写300个字而你却写了600个字。

　　He neednt have bought such a large house.His wife would have been quite happy in a cottage.

　　他没必要买这么大一所房子。他的妻子住在一个小房子里也会感到很满意的。(浪费了钱)

　　You neednt have carried all these parcels yourself.The shop would have delivered them if you had asked them.

　　你本来没有必要自己拿着这些大包小裹的。要是当时你跟商店说一声，他们就会把东西送来的。

　　B didnt have/need to do意指不一定非干某事，而通常也并没有这样做：

　　I didnt have to translate it for him for he understands Dutch.

　　我用不着替他翻译，因为他懂荷兰语。

　　I didnt have to cut the grass myself.My brother did it.

　　我用不着自己修剪草坪。我的兄弟修剪过了。(无义务，而且无行动)有些人的确把didnt have to/didnt need to用于表示已完成的动作，这时 have或 need都要加以重读：You didnhave to give him my name通常意味着没有必要告诉他我的姓名，但是你却告诉了他。但当一个不必要的动作实际已完成了时，还是用neednt have+过去分词为好：

　　You neednt have given him my name.

　　你本来没必要把我的姓名告诉他的。