it做形式主语用法大全含练习及答案.doc

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，wise
6.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.whenever
2.Infactisahardjobforthepolicetokeeporderinanimportantfootballmatch.(2001上海)
A.thisB.thatC.thereD.it
3.isafactthatEnglishisbeingacceptedasaninternationallanguage.(NMET1995)
A.ThereB.ThisC.ThatD.It
4.Isnecessarytotakeoffourshoeswhenweenterthelab?(MET88)
A.everyoneB.thisC.herD.it
5.________willtakeyoualotoftimetofindhiminthe