选修6Module1语法(外研社)
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选修6 Module1
didn’t need to do和needn’t have done
一、need用作情态动词时,没有词形的变化,后面接动词原形,通常用在否定句和疑问句
中。
He needs not pay for it.错
He needed not pay for it.错
He need not/needn’t pay for it.对
回答need提问的问句与回答must提问的问句一样,肯定回答用must(口语中也可以用have to);否定回答用needn’t或don’t have to。
—Need/Must I go at once?
—Yes, you must./No, you needn’t(或don’t have to).
二、need用作实义动词时,和其他普通的实义动词一样,有时态、人称和数的变化,其否
定式和疑问式要借助于助动词do,does,did。
need to do sth.有必要做某事
need to be done=need doing 需要被做
The flowers need to be watered./ watering.
三、didn’t need to do sth.没有必要做某事实际上也没有做,也可用didn’t have to代替,其中
的need为实义动词。
He didn’t need to go to school yesterday, and he went picnicking with his friends.
四、needn’t have done sth.过去本来不必做某事而实际上却做了
He needn’t have told you about it.
could have done本来可以做(而实际上未做)
may/might have done或许已经做(表推测);本来可以做(而实际上未做)
should/ought to have done本应该做(而实际上未做)
must have done(表推测)想必/准是/一定做了。