英语中it用法省公共课一等奖全国赛课获奖课件.pptx

it使用方法it用作主语指代天气、时间、距离、季节、事物状态和自然环境等Itisgettingcolderandcolder.ItistwoyearssinceIlastsawyou.Itwasveryquietinthecafe.HowisitwithMr.Rose?Itisonlytwentyminutes'drivetoourcollege.it作形式主语，代替不定式、动名词或从句，使原来这些主语能够放在句子后面，防止句子头重脚轻。1.it代替不定式作主语Itcostme$25tobuythedictionary.IsitnecessarytocompletethedesignbeforeNationalDay?It'sagoodideatohavealittlenotebookhandby.注意：有时不定式前面有一个for引发短语，表示不定式逻辑上主语，用it作形式主语时，组成下面句型Itis+adj.+forsb.+todo此句型中形容词为静态形容词，即描写人或物静态特征形容词，用来表示客观情况。这么形容词有：easy,difficult,important,hard,necessary,essencial,impossible,dangerous,common,unusual,big,small,tall,long,short,wide,old,young,beautiful等ItisverydifficutformetolearnSpanish.Itisgettinghardereverydayforapoormantogetaliving.注意：有时不定式前面有一个of引发短语，表示不定式逻辑上主语，用it作形式主语时，组成下面句型：Itis+adj.+ofsb.+todo此句型中形容词为动态形容词，即指那些有动作含义词，或为描写人或物特征或品质形容词，这么形容词有：bold,brave,busy,careful,careless,clever,considerate,cruel,foolish,friendly,generous,good,honest,kind,lazy,nice,noisy,polite,rude,reasonable,selfish,shy,silly,stupid,thoughtful,wicked等Itwasgenerousofyoutocontributesomuch.Itwascarelessofhertoloseherkeyofthesafe.2.it代替动名词作形式主语，而作主语动名词常放在表语后，在此句型中表语有以下名词和形容词：nogood,nouse,awasteoftime,fun,hardwork,pity,awonder,dangerous,difficult,senseless,useless,foolish,nice,hard,interesting,worth,worthwhile,terrible,tiring,funnyIt’snousestudyingforanexamatthelastminute.Itisdifficultfindingyourwayaroundhere.3.it代替从句作主语，有以下四个常见句型1)It+be+adj.+that从句这么adj通常有：possible/probable/likely很可能impossible/unlikely不可能obvious显而易见certain很必定plain很显著true真clear很清楚fortunate幸运是Itwasquiteplainthatshedidn'twanttocome.Howisitpossiblethatamancanfallsolow?注意：当形容词为以下形容词时，从句可用虚拟语气,为（should+）动词原形advisable适当，合理地better很好preferable优越，很好essential必要important主要insistent坚持natural自然necessary必要desirable理想urgent紧迫unfair不公平Itisunfairthatsomanypeopleshouldlosetheirjobs.Itisessentialthatyou(should)winthevoters'hearts.Itisimportantthatthismissionnotfail.2)it+be+n.+that从句commonknowledge常识anhonour非常荣幸ashame可耻awonder是个奇迹nowonder不足为奇afact事实goodnews好消息apity遗憾aquestion问题Itisawonderthatheisstill