it做形式主语用法大全含练习及答案It作形式主语常见句型动词不定式，动名词或主语从句作主语时，通常把它们放在谓语动词前，而用it作形式主语，放到句首，常见句型有:1.It+be+形容词+主语从句，如:ItisuncertainwhetherhecancometoJenny’sbirthdaypartyornot.2.It+be+名词词组+主语从句，这类名词有:afact,apity,ashame,anhonour，aquestion等，如:It’sapitythatyoumissedtheexcitingfootballmatch.Itremainsaquestionwhetherhewillcomeornot.3.It+be+过去分词+主语从句，这类过去分词有:announced,believed,expected,hoped,decided,reported,said,shown等，如:Itisreportedthat16peoplewerekilledintheearthquake.Itisnotdecidedwhowillgivetheoperationtothepatient.4.It+不及物动词(seem,appear,happen等)+主语从句,这类不及物动词有:appear,happen,seem等，如:Itseemedthathedidn’ttellthetruth.IthappenedthatIwasoutwhenhecalled.5.It+be+形容词+forsb.)+动词不定式这类句型常用形容词easy,difficult,hard,important,possible，wise等作表语，有时候为了强调不定式动作的执行者，常在不定式前加forsb，如:It’snecessaryfortheyoungtomastertwoforeignlanguage.Itisunwisetogivethechildrenwhatevertheywant.这类形容词有:easy,difficult,hard,important,possible，wise6.It+be+形容词+ofsb.+动词不定式，这类形容词常是表示心理品质,性格特征的形容词，如:kind,nicestupid,clever,foolish,polite,impolite,silly,selfish,considerate等。某人和这些形容词可以构成主系表结构。如:It’sverykindofyoutohelpmewiththework.=Youarekindtohelpme.Itseemedselfishofhimnottosharehisdictionarywithothers.=Heseemedselfishnottosharehisdictionarywithothers.7.It+be+名词词组+动词不定式，如:Itisnotagoodhabittostayuptoolate.8.It+be+名词或形容词+动名词，这类名词和形容词常常是:good,nogood,nouse,awasteof,useless,senseless等，如:It’sawasteoftimetalkingtoheranymore.Itisnousearguingaboutthematterwithhim.9.It+take(sb.)+时间(金钱)+动词不定式，如:Ittooktheworkersalmostthreeyearstofinishbuildingthedam.Itwilltakeawholedaytogettothetopofthemountainonfoot.实战演练:1.Itisgenerallyconsideredunwisetogiveachildheorshewants.(NMET1997)A.howeverB.whateverC.whicheverD.whenever2.Infactisahardjobforthepolicetokeeporderinanimportantfootballmatch.(2001上海)A.thisB.thatC.thereD.it3.isafactthatEnglishisbeingacceptedasaninternationallanguage.(NMET1995)A.ThereB.ThisC.ThatD.It4.Isnecessarytotakeoffourshoeswhenweenterthelab?(MET88)A.everyoneB.thisC.herD.it5.________willtakeyoualotoftimetofindhiminthecrowd.A.ItB.IC.WeD.They6.Itisnousehis_________there,thesituationishopelessnow.A.togoB.tobegoingC.goingD.havinggone7.Itisnevertoolatetolearn,________?A.isitB.isn’titC.doesitD.doesn’tit8.___________isknowntoallthatShenzhouVILaunchedSuccessfully.A.AsB.WhatC.ItD.That9._______isreportedinthenewspaper,theEarthquakeineastChina'sJiangxi Province killed 13
people
A. It B. As C. That D. What
10. ___________ certain that his invention will make people’s life
convenient.
A. That’s B. This is C. It’s D. What’s
11. _________ that there is another football match on the air this
evening.
A. It says B. It was said C. It is said D. What was said 12.
__________ that their daughter got an opportunity to study abroad.
A. It’s a exciting news B. This is an exciting news
C. This is exiting news D. It’s exciting news
参考答案:
1——5 BDDDA 6——10CACAC 11——12CD
? it 作形式主语:
it 作形式主语时没有具体的意义，而只是帮助把真正的主语移到句子后部去，
使句子显
得平稳一些。it 作形式主语时，可以代替三种形式:不定式、动名词和主语从
句。
? it 代替不定式短语
常用于下列句型中:It + be +形容词 + (for/of sb.) to do sth.
It + be + 名词 + to do sth.
It takes sb. some time to do sth. 干„花了某人„时间
It’s up to sb. to do sth. 干„是某人的职责或义务
?It is everyone’s duty to obey the law.
遵守法律是每个人的义务。( it 作形式主语, 代替不定式短语to obey the
law)
?It is difficult for a foreigner to learn Chinese.
对于一个外国人来说，学习汉语是困难的。
( it 作形式主语, 代替不定式短语to learn Chinese)
?It is not right to use these places as rubbish dumps.
把这些地方用来倒垃圾是不对的。
(it 作形式主语, 代替不定式短语to use these places as rubbish dumps)
?It took them a year to build the bridge.
建这座桥花了他们一年的时间。( it 作形式主语, 代替不定式短语to build
the bridge)
? It be + 形容词+ for sb. to do sth.与It be + 形容词+of sb. to do
sth.:
如果句型中的形容词描述的是sb.的品质、品格，在逻辑上可以作sb.的表
语，则sb.前应用介词of，否则就用for。
?It’s necessary for us to use a short-wave radio to pick up the
programmes.
我们用一台短波收音机收听这些节目是必要的。
?It’s kind of you to help me.
感谢你对我的帮助。(= You are kind to help me. )
?It was foolish of him to give up the job.
他放弃那工作是愚蠢的。(= He was foolish to give up the job
? it 代替动名词短语:
动名词作主语用后置形式的情况远不及不定式那么普遍，常限于no good, no
use, useless, waste 等词的后面。
?It is no good/ use having a car if you can’t drive.
如果你不会开车，有车也没用。( it 作形式主语,代替动名词短语having a
car)
?It is a waste of time watching TV.
看电视是浪费时间。( it 作形式主语,代替动名词短语watching TV)
It is no use asking him. ?
问他没有用。( it 作形式主语,代替动名词短语asking him)
? it 代替主语从句:
这个主语从句可以用连词that 引导，也可以用连接代词或连接副词引导。
?It was clear that they had no desire for peace.
很清楚他们没有和平的诚意。
( it 作形式主语,代替主语从句that they had no desire for peace)
?It is doubtful whether she will be able to come.
