It作形式主語教學設計動詞不定式，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，如：ItisuncertainwhetherhecancometoJenny’sbirthdaypartyornot.2.It+be+名詞詞組+主語從句，這類名詞有：afact,apity,ashame,anhonour，aquestion等，如：It’sapitythatyoumissedtheexcitingfootballmatch.Itremainsaquestionwhetherhewillcomeornot.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：Itseemedthathedidn’ttellthetruth.IthappenedthatIwasoutwhenhecalled.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，有時候為了強調不定式動作的執行者，常在不定式前加forsb，如：It’snecessaryfortheyoungtomastertwoforeignlanguage.Itisunwisetogivethechildrenwhatevertheywant.這類形容詞有：easy,difficult,hard,important,possible，wise6.It+be+形容詞+ofsb.+動詞不定式，這類形容詞常是表示心理品質,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成主系表結構。如：It’sverykindofyoutohelpmewiththework.=Youarekindtohelpme.Itseemedselfishofhimnottosharehisdictionarywithothers.=Heseemedselfishnottosharehisdictionarywithothers.7.It+be+名詞詞組+動詞不定式，如：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’sawasteoftimetalkingtoheranymore.Itisnousearguingaboutthematterwithhim.9.It+take(sb.)+時間（金錢）+動詞不定式，如：Ittooktheworkersalmostthreeyearstofinishbuildingthedam.Itwilltakeawholedaytogettothetopofthemountainonfoot.鑒于it做形式主語有這如此多用法，我對微課教學設計做出如下安排：TeachingTopic:Itisusedastheformalsubject.Teachinggoals:Enablestudentstograsptheformalsubject.Enablestudentstoknowhowtheformalsubjectcomes.Enablestudentstounderstandthisgrammaranduseitfreely.Teachingkeypointsanddifficultpoints:Keypoints:Knowthatitcanreplacethesubjectclauseasthesubject.Difficultpoints:InthestructureIt+be+pastparticiple+subjectclause,ifthepastparticipleisadvised,suggestedororderedandsoon,thesentencemustusethesubjunctivemood.TeachingProcedures:Useasentence:Thatourschoolwillholdafootballgameisknowntoustoleadtheformalsubjectit.Throughtheexplanationandpicture,letstudentsunderstanditandknowthatitdoesn’thaverealmeaninginthisstructure.Thenshowfivekindsoftheusageoftheformalsubjectit.It+be+adj.+thesubjectclause.Inthispart,Imakethelistofmanyadjectivesthatarealwaysusedinthissentencepattern.ThenIuseaChinesesentenceandapicturetoleadstudentstoputthisstructureintouse.It+be+nounphrases+thesubjectclause.Inthispart,Imakethelistofmanynounphrasesthatarealwaysusedinthissentencepattern.ThenIuseaChinesesentenceandapicturetoleadstudentstotranslateasentenceusingthisstructure.It+be+thepastparticiple+thesubjectclause.Imakethelistofmanypastparticiplesthatareusedinthissentencepattern.Thenuseasentenceandapicturetoshowit.ThenIemphasizethesubjunctivemoodthatexistsinthisstructure.It+be+vi+thesubjectclause.Makethelistofmanyintransitivesusedinthisstructure.Iuseasentenceandapicturetomakestudentsunderstandwhattheyhavelearnedbetter.It+be+transitiveverbs+thesubjectclause.Makethelistofsometransitiveverbs.Useasentenceandapicturetomakestudentsunderstandthissentencepatternwell.3.SummarySummarizethefivekindsoftheusagetheformalsubject.實戰演練：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'sJiangxiProvincekilled13peopleA.ItB.AsC.ThatD.What10.___________certainthathisinventionwillmakepeople’slifeconvenient.A.That’sB.ThisisC.It’sD.What’s11._________thatthereisanotherfootballmatchontheairthisevening.A.Itsays