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题目
must have done 与 may have done 的反义疑问句
详解

提问时间:2020-06-03

答案
情态动词+动词完成时,即情态动词+have+done.表示对过去的行为或动作进行推测,评论或者判断.
1.must have done.
表示对过去某事的肯定猜测,其否定或疑问形式都用can/could来表示.
例如:since the road is wet,it must have rained last night.
2;当然对现在发生或者将来发生的事情,要用must do表示猜测,否定为can’t do
he must understand that we mean business.
you must be hungry after a long walk.
反意疑问句中含有Must的情况主要有以下几种:
1)作为情态动词表“必须”,这时反意疑问句直接用mustn'/needn't
2)当must表示推测时又分以下几种情况:
a:对现在事实的推测,反意疑问句与must后面的动词呼应,如:
You must be joking,aren't you
b:对过去事实的推测,表示动作的时候用did 当助动词,表示状态时用was,如:
Mr Green must have been punished for his being rude at the meeting,didn‘t he (格林先生一定因为昨天在会上鲁莽的行为被处罚了,是吗?) 被处罚表示一个动作
She must have been a policeman ,wasn't she (她过去一定是个警察,是吗?) 是警察表示一种状态
对现在情况的推测,问句部分用主动词(do,be)一般现在时的适当形式.若是现在进行时,问句部分用现在进行时的适当形式表示.若是there be结构,问句用isn't/aren't there.如:
1)He must be there,isn't he?
2)He must have a big family,doesn't he?
3)He must be waiting outside,isn't he?
4)There must be some students in the room,aren't there?
对已发生的过去情况的推测,若陈述句谓语部分有“must have done”,而且有表示过去的时间状语,问句部分用didn't;若没有表示过去的时间状语,问句部分用haven't或hasn't.如:
1)They must have gone there last night,didn't they?
2)They must have arrived by now,haven't they?(根据by now来判断)
3)They must have been to the Great Wall,haven't they?
若是被动,应按被动结构来处理.如:
1)The room must have been cleaned yesterday,wasn't it?
2)The room must have been cleaned,hasn't it?
若句中有表示过去完成时的时间状语,问句部分应用hadn't.如:
They must have learnt 5000 English words by the end of last term,hadn't they?
(本题中must表推测,如果将它去掉,还原为真实句就是They had learnt 5000 English words by the end of last term.因此,反意问句是hadn't)
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