高中英语语法

19.2用it作主语的句子19.2.1用it作人称代词（personalpronoun）1）it最基本的用法是作人称代词，主要代表刚提到的东西以避免重复：Didtheblacksnakefrightenyou?–Yes,itdid.Lookatthatcar.It’sgoingmuchtoofast.“Where’smycoat?”“It’sinthecupboard.”2）也可代表抽象的事物：Thegovernmenthasbecomeveryunpopularsinceitintroducedthenewtax.Itwasagreatsurprisetomewhenhedidathinglikethat.“I’vebrokenthemirror.”“Itcan’tbehelped.”It’sallmyfault.3）也可以指动物或未知性别的婴儿：“Isthisyourdog?”“No,itisn’t.”Hernewbabyistiny.Itonlyweighs2kilos.Whatabeautifulbaby—isitaboy?4）还可代表一个彼此都知其何所指的东西：Doesititchmuch？Wheredoesithurt?It’smeningitis.19.2.2非人称代词itIt有时并不指具体东西，而指天气、时间、环境等，称为非人称代词it（impersonalit），可以：1）指天气：It’sraining(snowing).It’sfrosty(alovelyday).It’safinenight(fullmoontonight).It’ssunny(abitwindy).Itwaspouringwithrain.Itwasverycold(quitewarm)attheweekend.2）指时间：It’sTuesdaytoday.It’snearlyhalfpasteight.It’sthethirdofJune.Itwastwilight(midnight)whentheycameoutofthehall.“Whattimeisit?”“It’stentoeleven.”It’sfiveyearssinceIsawyoulast.It’sourweddinganniversary.3）指环境：Itgetsverycrowdedhereinthesummer.It’slovelyhere.It’squiet(verynoising)here.They’resuretoseeyou.It’sbrightmoonlight.It’snicedownthere.It’sgettingsodark.4）指距离：HowfarisittoKunming?It’stwomilestothebeach.It’s112milesfromLondontoBirmingham.It’shalfanhour’swalktothecitylibrary.It’sonlytwentyminutes’drivetoouruniversity.Howfarisitfromyourhometoyouroffice?It’saboutanightjourneytothisplacebytrain.19.2.3用于强调的it1）it可用来对句子的某一成分加以强调，例如NancysawyoursisterinTokyolastweek.可改为许多强调结构：、ItwasNancywhosawyoursisterinTokyolastweek.（强调主语）ItwasyoursisterwhomNancysawinTokyolastweek.（强调宾语）ItwasinTokyothatNancysawyoursisterlastweek.（强调状语）ItwaslastweekthatNancysawyoursisterinTokyo.（强调状语）从这些句子可以看出这类句子的结构是：It+动词be+强调部分+who(m)或that+其他部分这类句子可称为分裂句（cleftsentence），这种结构成为分裂结构（cleftstructure）。2）在强调主语时，可用who（间或用that）引导后面部分：ItwasPeterwholentusthemoney.Itwasyouwhohadbeenwrong.Wasityouwho(that)brokethewindow?Whowasitthatcalledthemeeting?若主语是物不是人，则需用that：Buthereit’smywordthatcounts.3）在强调宾语或介词宾语时，若是人关系代词用whom，间或用that（a），若是物则需用that（b）：a.It’sTomwhomyoushouldask.ItwasJiminwhomshestillhadherfaith.ItwasPeterwithwhomIfirstcameincontact.Itwasthepresidentthat(whom)Jeanshotyesterday.It’smethatheblamed.It’spilotsthatweneed,notgroundstaff.b.It’smoneythattheywant.It’sSpainthatthey’regoingto,notPortugal.ItwasakeythatIfoundthere.4）在强调状语时后面多用that：ItwasonMondaynightthatallthishappened.It’stodaythathe’sgoing.ItwasherethathechieflydifferedfromanEnglishman.Whyisitthatyouobjecttotheidea?5）在口语中，who,that这类关系代词有时省略：IthinkitwasGoethesaidthis.ItwasPhilipdroveMissSophiayesterday,wasn’tit?ItwasyouIthoughtofallthetime.ItwasthenIheardPhuong’ssteps.Whatisityouwantmetode?Wasitin1980thishappened?6）有些否定句也可改成这种强调结构： Ididn’thearfromheruntillastsummer. Itwasn’tuntillastsummerthatIheardfromher. Ididn’tdoallthisformyself. Itwasn’tformyselfthatIdidallthis.. Ididnothaveanopportunityofseeingheragainforseveralyears. Itwasn’tforseveralyearsthatIhadanopportunityofseeingheragain.问句也可变成这种结构： Whocalledhim“comrade”? Whowasitthatcalledhim“comrade”? WhydoeseveryonethinkI’mnarrow-minded? WhyisitthateveryonethinksI’mnarrow-minded? Howdidyouforgettolockthedoor? Howwasitthatyouforgottolockthedoor?19.2.4先行主语it1）it可以用作先行词，作为句子形式上的主语，而把真正的主语移到句子后部去。这可使句子变得更平稳，不致主语太长，显得头重脚轻。这种it称为先行主语（preparatorysubject）。可移到句子后部去的主语最常见的是不定式。句子谓语可有下面几种类型：a.be+形容词+不定式：Itiseasytocriticizeothers.It’sbettertobeearly.It’sabsurdtobeafraid.It’snicenottobedependentonthem.b.be+名词+不定式：Itwashisdutytotakecareoftheorphans.It’saprivilegetovisityourcountry.Itwouldbeapitytomissthisopportunity.Itwasnotmyhabittoaskpeopleforthings.c.be+介词短语+不定式：Itwasagainstmyprincipletodothat.It’sbeyondmetosaywhy.It’snotwithinmypowertohelpthem.It’sunlikehimtobelate;he’susuallyontime.d.及物动词+宾语+不定式：Itcost100dollarstorepairthecar.Itgavemegreatpleasuretowatchthem.