情態(tài)動(dòng)詞+動(dòng)詞完成時(shí),即情態(tài)動(dòng)詞+have+done.表示對(duì)過(guò)去的行為或動(dòng)作進(jìn)行推測(cè),評(píng)論或者判斷.
1.must have done.
表示對(duì)過(guò)去某事的肯定猜測(cè),其否定或疑問(wèn)形式都用can/could來(lái)表示.
例如：since the road is wet,it must have rained last night.
2；當(dāng)然對(duì)現(xiàn)在發(fā)生或者將來(lái)發(fā)生的事情,要用must do表示猜測(cè),否定為can’t do
he must understand that we mean business.
you must be hungry after a long walk.
反意疑問(wèn)句中含有Must的情況主要有以下幾種：
1）作為情態(tài)動(dòng)詞表“必須”,這時(shí)反意疑問(wèn)句直接用mustn'/needn't
2)當(dāng)must表示推測(cè)時(shí)又分以下幾種情況：
a：對(duì)現(xiàn)在事實(shí)的推測(cè),反意疑問(wèn)句與must后面的動(dòng)詞呼應(yīng),如:
You must be joking,aren't you
b:對(duì)過(guò)去事實(shí)的推測(cè),表示動(dòng)作的時(shí)候用did 當(dāng)助動(dòng)詞,表示狀態(tài)時(shí)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?yàn)樽蛱煸跁?huì)上魯莽的行為被處罰了,是嗎?） 被處罰表示一個(gè)動(dòng)作
She must have been a policeman ,wasn't she （她過(guò)去一定是個(gè)警察,是嗎?） 是警察表示一種狀態(tài)
對(duì)現(xiàn)在情況的推測(cè),問(wèn)句部分用主動(dòng)詞（do,be)一般現(xiàn)在時(shí)的適當(dāng)形式.若是現(xiàn)在進(jìn)行時(shí),問(wèn)句部分用現(xiàn)在進(jìn)行時(shí)的適當(dāng)形式表示.若是there be結(jié)構(gòu),問(wèn)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?
對(duì)已發(fā)生的過(guò)去情況的推測(cè),若陳述句謂語(yǔ)部分有“must have done”,而且有表示過(guò)去的時(shí)間狀語(yǔ),問(wèn)句部分用didn't；若沒(méi)有表示過(guò)去的時(shí)間狀語(yǔ),問(wèn)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?（根據(jù)by now來(lái)判斷）
3)They must have been to the Great Wall,haven't they?
若是被動(dòng),應(yīng)按被動(dòng)結(jié)構(gòu)來(lái)處理.如：
1)The room must have been cleaned yesterday,wasn't it?
2)The room must have been cleaned,hasn't it?
若句中有表示過(guò)去完成時(shí)的時(shí)間狀語(yǔ),問(wèn)句部分應(yīng)用hadn't.如:
They must have learnt 5000 English words by the end of last term,hadn't they?
(本題中must表推測(cè),如果將它去掉,還原為真實(shí)句就是They had learnt 5000 English words by the end of last term.因此,反意問(wèn)句是hadn't）
嘿嘿,給我分成不成~.- -