【定义】一个句子在另一个句子中充当主语、宾语、表语、同位语,相当于名词,故称为名词性从句。【四大从句】名词性从句分为主语从句、宾语从句、表语从句和同位语从句。一、主语从句一个句子在另一个句子中充当主语,即句子充当主语,该句子称为主语从句。【完成例句】根据句意选词填空(that,if,whether,why,when,what)(1)Thathewillsucceediscertain.(2)Whetherhewillgothereisnotknown.(3)Whathesaidisnottrue.(4)Whenthemeetingwillbeheldhasnotbeendecidedyet.【结论】①that-从句,从句为一个句意完整的陈述句,没有具体意义,不充当句子成分,只起标志性作用,但that不能省略。②whether-从句,从句来源于一般疑问句,whether不能省略,意为“是否”,不能用if替换。③特殊疑问词-从句,从句来源于特殊疑问句,特殊疑问词不能省略,意思为特殊疑问词本来的意思,在从句中充当句子成分。【疑难1】Whoheisisnoneofmybusiness.【疑难剖析1】任何从句要用陈述句语序,即主谓语序。【疑难2】ThathelikesEnglishisknowntousall.Whathesaidatthemeetingmademesad.【疑难剖析2】主句时态为过去时,从句时态为过去的某一时态;主句时态为现在时或将来时,从句时态视具体情况而定。【疑难3】That2010AsianGamesaresuccessfulisknowntoall.【疑难剖析3】单个句子作主语,视为单数。【疑难3】Itisapitythatyoudidn'tgotoseethefilm.Itdoesn'tinterestmewhetheryousucceedornot.Itisinthemorningthatthemurdertookplace.ItisJohnthatbrokethewindow.【疑难剖析3】1.主语从句通常由it充当形式主语,而本身放在句子末尾。2.it作形式主语和it引导强调句的比较it作形式主语代替主语从句,主要是为了平衡句子结构,主语从句的连接词没有变化。而it引导的强调句则是对句子某一部分进行强调,无论强调的是什么成分,都可用连词that。被强调部分指人时也可用who/whom。3.用it作形式主语的常用结构①Itis+名词+从句Itisafactthat…事实是……Itisanhonorthat…非常荣幸Itiscommonknowledgethat………是常识②Itis+形容词+从句Itisnaturalthat…很自然……Itisstrangethat…奇怪的是……③Itis+不及物动词+从句Itseemsthat…似乎……Ithappenedthat…碰巧……Itappearsthat…似乎……④It+过去分词+从句Itisreportedthat…据报道……Ithasbeenprovedthat…已证实……Itissaidthat…据说……【疑难5】ItissaidthatChairmanHuwillvisitourschoolnextweek.(√)ThatChairmanHuwillvisitourschoolnextweekissaid.(×)【疑难剖析5】主语从句不可位于句首的五种情况:1.if引导的主语从句不可位于复合句句首。2.Itissaid/reported…结构中的主语从句不可提前。3.Ithappens/occurs…结构中的主语从句不可提前。Itoccurredtohimthathefailedintheexamination.(√)Thathefailedintheexaminationoccurredtohim.(×)4.Itdoesn'tmatterhow/whether…结构中的主语从句不可提前。Itdoesn'tmatterwhetherheiswrongornot.(√)Whetherheiswrongornotdoesn'tmatter.(×)5.含主语从句的复合句是疑问句时,主语从句不可提前。Isitlikelythatitwillrainintheevening?(√)Isthatwillrainintheeveninglikely?(×)【疑难6】what与that在引导主语从句时的区别Whatyousaidyesterdayisright.Thatsheisstillaliveisaconsolation.【疑难剖析6】what引导主语从句时在从句中充当主语、宾语或表语,而that则不充当任何成分。二、宾语从句在复合句中作宾语的名词性从句是宾语从句,通常放在主句谓语动词(及物动词)或介词之后。【完成例句】根据句意选词填空(that,if,whether,where,what,who)(5)Iheardthathejoinedthearmy.(6)Shedidnotknow①whathadhappened.②Iwonderwhetheryoucanchangethisnoteforme.(7)Shetoldmethatshewouldacceptmyinvitation.【结论9】①由that引导的宾语从句(that通常可以省略),that在从句中不充当任何成分。②由what引导的宾语从句,what在从句中充当主语、宾语或表语。③whether(if)引导的宾语从句,在从句中不充当任何成分,只起连接作用,意为“是否”。【疑难1】引导宾语从句时if和wheth...