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1、If引导条件句的用法1、真实条件句用于陈述语气,假设的情况可能发生,其中if是如果的意思。 时态关系句型:条件从句 主句 一般现在时 shall/will+动词原形Ifhecomes,hewillbringhisviolin.典型例题Thevolleyballmatchwillbeputoffifit___. A.willrain B.rains C.rained D.israined答案B。真实条件句主句为将来时,从句用一般现在时。注意:1)在真实条件句中,主句不能用begoingto表示将来,该用shall,will. (错)Ifyouleaveno
2、w,youarenevergoingtoregretit.(对)Ifyouleavenow,youwillneverregretit. 2)表示真理时,主句谓语动词便不用shall(will)+动词原形,而直接用一般现在时的动词形式。 2非真实条件句1)时态:可以表示过去,现在和将来的情况。它的基本特点是时态退后。a. 同现在事实相反的假设。句型:条件从句 主句 一般过去时 should(would)+动词原形 Iftheywerehere,theywouldhelpyou.b. 表示于过去事实相反的假设。句型:条件从句 主句 过去完成
3、时 should(would)have+过去分词 Ifshehadworkedharder,shewouldhavesucceeded. Thericewouldnothavebeenburntifyouhadbeenmorecareful. IfmylawyerhadbeenherelastSaturday,hewouldhavepreventedmefromgoing. Ifhehadcomeyesterday,Ishould/wouldhavetoldhimaboutit. 含义:Hedidnotcomeyesterday,soIdidnott
4、ellhimaboutit.Ifhehadnotbeenillandmissedmanyclasses,hewouldhavemadegreaterprogress.含义:Hewasillandmissedmanylessons,sohedidnotmakegreaterprogress. c. 表示对将来的假想 句型: 条件从句 主句 一般过去时 should+动词原形were+不定式 would+动词原形should+动词原形 Ifyousucceeded,everythingwouldbeallright. Ifyoushoulds
5、ucceed,everythingwouldbeallright.Ifyouweretosucceed,everythingwouldbeallright. 3混合条件句主句与从句的动作发生在不同的时间,这时主,从句谓语动词的虚拟语气形式因时间不同而不同,这叫做混合条件句。 Ifyouhadaskedhimyesterday,youwouldknowwhattodonow.(从句与过去事实相反,主句与现在事实相反。) Ifithadrainedlastnight(过去),itwouldbeverycoldtoday(现在).4虚拟条件句的倒装 虚拟条件句的从句部
6、分如果含有were,should,或had,可将if省略,再把were,should或had移到从句句首,实行倒装。 Weretheyherenow,theycouldhelpus.=Iftheywereherenow,theycouldhelpus. Hadyoucomeearlier,youwouldhavemethim =Ifyouhadcomeearlier,youwouldhavemethim. Shoulditrain,thecropswouldbesaved. =Wereittorain,thecropswouldbesaved.注意: 在虚
7、拟语气的从句中,动词’be’的过去时态一律用"were",不用was,即在从句中be用were代替。 IfIwereyou,Iwouldgotolookforhim.如果我是你,就会去找他。 Ifhewerehere,everythingwouldbeallright. 如果他在这儿,一切都会好的。典型例题 _____todothework,Ishoulddoitsomeotherday.A.IfwereI B.IwereC.WereID.WasI 答案C.在虚拟条件状语中如果有were,should,had这三个词,通常将if省略,主语提前,变成were
8、,should,had+