It做形式主语讲解

,It做形式主语,Itsnecessaryfortheyoungtomastertwoforeignlanguage.,Itsawasteoftimetalkingtoheranymore.,Itsapitythatyoumissedtheexcitingfootballmatch.,动词不定式,动名词,从句,形式主语,It作为形式主语的用法,当不定式、动名词、从句等用作句子主语时，为保持句子平衡，通常把真正的主语放在句末，而在句首使用形式主语it.,拒绝是令人遗憾的.,记住这一点是很重要的.,Itsapitytorefuse.,Itsveryimprotanttorememberthis,一、代替动词不定式做形式主语,It+be+adj.+（forsb.）todosth.此处adj.通常为描述事件的形容词：easy，difficult，hard，necessary，impossible，important，natural,likely，obvious，useful，useless，dangerous做某事是Itsnecessaryforustomasteraforeignlanguage.,It+be+adj.+ofsb.todosth此处adj.通常为描述人的形容词：kind，nice，rude，cruel，careless，foolish，stupid，wise，crazy某人做某事，某人是eg.Itsfoolishofyoutodriveacarafterdrinking.ItsverykindofyoutohelpmewithmyEnglish.,It+be+名词词组+动词不定式eg.Itisnotagoodhabittostayuptoolate.常见句型：Ittakes/tooksb.sometime/moneytodosth.,Itisnogoodcryingoverspiltmilk.,Itisnousecastingpearlsbeforeswine.,覆水难收,不要明珠暗投，对牛弹琴,构成如下结构：Itis+nouse/nogood/notanygood/notanyuse+doingsth.,二、代替动名词作形式主语,It+be+名词词组+主语从句这类名词有：afact,apity,ashame,anhonour，aquestion，asurprise，commonknowledgeeg.Itscommonknowledgethatpeoplecanntlivewithoutwater.,三、代替从句做形式主语,It+不及物动词+that（asif）-从句这类不及物动词有：look，seem，appear，happen，occureg.Itseemsthathedoesnottellthetruth.,Itistime+thatsb.+v-ed/shoulddoEg.ItstimethatyouwenttobedItstimethatyoushouldgotobed.Itsnecessary/impossible/important/naturalthatsb.(should)doEg.Itsimportantthatwe(should)keepthebalanceofnature.,It+be+adj.+that-从句,It+be+-ed（过去分词）+that-从句,Itissaidthat据说Itisreportedthat据报道Itissupposedthat据推测Itishopedthat希望Itiswellknownthat众所周知Itisgenerallyconsideredthat普遍认为Itissuggestedthat有人建议,练习：把下列格局转换为it做形式主语的句子,1.Hewasrudetosayso.2.Tryingagainisofuse.3.Whenandwheretoholdthepartyhasntbeendecided.,Itwasrudeofhi