1、,知識點it作形式主語,it作形式主語,【知識點解析】,動詞不定式，動名詞或主語從句作主語時，通常把它們放在謂語動詞前，而用it作形式主語，放到句首，常見句型有：1.It+be+形容詞+主語從句ItisuncertainwhetherhecancometoJennysbirthdaypartyornot.2.It+be+名詞詞組+主語從句這類名詞有：afact,apity,ashame,anhonor,aquestion等，如：Itsapitythatyoumissedtheexcitingfootballmatch.Itremainsaquestionwhetherhewillcomeorn

2、ot.,it作形式主語,【知識點解析】,3.It+be+過去分詞+主語從句這類過去分詞有：announced,believed,expected,hoped,decided,reported,said,shown等，如：Itisreportedthat16peoplewerekilledintheearthquake.Itisnotdecidedwhowillgivetheoperationtothepatient.4.It+不及物動詞(seem,appear,happen等)+主語從句這類不及物動詞有：appear,happen,seem等，如：Itseemedthathedidnttell

3、thetruth.IthappenedthatIwasoutwhenhecalled.,it作形式主語,【知識點解析】,5.It+be+形容詞+forsb.）+動詞不定式這類句型常用形容詞easy,difficult,hard,important,possible,wise等作表語，有時候為了強調(diào)不定式動作的執(zhí)行者，常在不定式前加forsb，如：Itsnecessaryfortheyoungtomastertwoforeignlanguage.Itisunwisetogivethechildrenwhatevertheywant.這類形容詞有：easy,difficult,hard,impor

4、tant,possible,wise,it作形式主語,【知識點解析】,6.It+be+形容詞+ofsb.+動詞不定式這類形容詞常是表示心理品質(zhì),性格特征的形容詞，如：kind,nicestupid,clever,foolish,polite,impolite,silly,selfish,considerate等。某人和這些形容詞可以構(gòu)成主系表結(jié)構(gòu)。如：Itsverykindofyoutohelpmewiththework.=Youarekindtohelpme.Itseemedselfishofhimnottosharehisdictionarywithothers.=Heseemedself

5、ishnottosharehisdictionarywithothers.,it作形式主語,【知識點解析】,7.It+be+名詞詞組+動詞不定式Itisnotagoodhabittostayuptoolate.8.It+be+名詞或形容詞+動名詞這類名詞和形容詞常常是：good,nogood,nouse,awasteof,useless,senseless等，如：,it作形式主語,【知識點解析】,Itsawasteoftimetalkingtoheranymore.Itisnousearguingaboutthematterwithhim.9.It+take(sb)+時間（金錢）+動詞不定式I

6、ttooktheworkersalmostthreeyearstofinishbuildingthedam.Itwilltakeawholedaytogettothetopofthemountainonfoot.,it作形式主語,【典型例題】,1.Infactisahardjobforthepolicetokeeporderinanimportantfootballmatch.A.thisB.thatC.thereD.it2.isimportanttodoyourhomework.(NMET1995)A.ThereB.ThisC.ThatD.It3.Isnecessarytotakeoffou

7、rshoeswhenweenterthelab?(MET88)A.everyoneB.thisC.herD.it,it作形式主語,【典型例題】,4._willtakeyoualotoftimetofindhiminthecrowd.A.ItB.IC.WeD.They5._isknowntoallthatShenzhouVIlaunchedsuccessfully.A.AsB.WhatC.ItD.That答案：1.D2.D3.D4.A5.C,it作形式主語,【典型例題】,解析：1.it作形式主語，指代后面的tokeeporderinanimportantfootballmatch2.it作形式主語，指代后面的todoyourhomework3.此句是選擇疑問句，it作形式主語，指代后面的totak