Unit3Ahealthylife-语法篇____________________________________________________________________________________________________________________________________________________________________1.掌握it的用法；2.理解并巩固it的各种用法并能正确使用；It的用法一、it作人称代词1.it的最基本用法是作代词，主要指刚提到的事物，以避免重复:Xi’anisabeautifulcity,isn’tit?2.也可以指动物或婴儿(未知性别的婴儿或孩子):Isthisyourdog?No,itisn’t.二、it作非人称代词it有时并不指具体的东西，而泛指天气、时间、日期、距离、价值、度量、温度、环境等，称为非人称的it：1.指天气：Itisalovelyday,isn’tit?Itisabitwindy.2.指时间：Itwasnearlymidnightwhenshecameback.3.指环境：Itwasveryquietinthecafé.4.指距离：Itishalfanhour’swalktothecitycentrefrommyhome.5.指日期：--What'sthedatetoday?--It'sMay1,2007.6.指季节：Itissummernow.7.指度量：Itisabout5kilograms.8.指价值：---What'sthecostoftheT-shirt?----Itis150yuan.三、it用作形式主语替代作主语的从句、动词不定式、动名词，而把真正作主语的从句、动词不定式、动名词置于句尾。1.代作主语的动词不定式(1)It+be+adj.+（forsb.）todosth.此处adj.通常为描述事件的形容词：easy,difficult,hard,necessary,unnecessary,possible,impossible,likely,unlikely,right,wrong,important,unimportant,legal,illegal,polite,impolite,clear,obvious,certain,suitable,proper,fit,useful,useless,dangerous…Itisillegal（forateenager）todriveacarwithoutalicense.(2)It+be+adj.ofsb.todosth.此处adj.通常为描述人的形容词：kind,unkind,nice,rude,cruel,considerate,thoughtful,thoughtless,careful,careless,silly,foolish,stupid,clever,wise,crazy.It'skindofyoutohelpmewiththeproblem.(3)It替代作主语的动名词的常见句型It'snogood/usedoing…It's（well）worthdoing…It's（well）worthwhiledoing/todoIt'snousecryingoverspiltmilk.2.it作形式主语替代主语从句①It+be+adj.+clauseItisclear(obvious,true,possible,certain…)that...该句型中it是形式主语，真正的主语是that引导的主语从句，常译为“清楚（显然,真的……）”是主语从句最常见的一种结构。例如：Itisveryclearthathe’sroundandtalllikeatree.②It+be+v-ed+that…=sb./sth.+be+todoItissaid(reported/learned/believed/thought/known/told/hoped.....)that...该句型中的it仍是形式主语，真正主语是that引导的主语从句；该结构常译为“据说（据报道，据悉...）”。Itisreportedthatanotherearthsatellitehasbeenputintoorbit.③It+be+noun+从句Itisapity/ashame+that...该句型中，that后的从句一般用虚拟语气（should+动词原形），should可省去.表示出乎意料，常译为“竟然”。没有这种意义时，则不用虚拟语气。Itisapitythatsuchathing(should)happeninyourclass.这种事竟然发生在你们班上，真是遗憾！Itisapitythatheisill.他生病了，真遗憾！四、it作形式宾语当复合宾语中的宾语是不定式、动名词宾语从句时，往往把宾语放在它的补足语后面，而用it作形式宾语，放在宾语补足语之前。该句型中的it作形式宾语，常用的动词有think,believe,make,find,consider,feel等。Ithinkitnousearguingwithhim.我认为和他争吵没有用。IfounditveryinterestingtostudyEnglish.我发现学英语非常有趣。Hemadeitclearthathewasnotinterestedinthissubject.他非常清楚地表示他对那门学科不感兴趣。五、用于强调句型中Itis/was+被强调部分+that/who...Itisnotuntil+被强调部分+that...Itwasfiveo’clock_________Igothome.Itwasatfiveo’clock_______Igothome.强调句用以强调主语，宾语，介词宾语以及状语。强调人时用that和who／whom皆可Itwasshewho／thathadbeenwrong.Itwasthegirlwhom／thatImetjustnow.ItwasTomtowhomtheteacherhadtalked.ItwasonMondaynightthatallthishappened.Itisnotuntil+被强调部分+that...该句型也是强调句型。主要用于强凋时...