定语从句1.基本知识精讲在复合句中修饰名词或代词的从句叫做定语从句。被定语从句修饰的名词或代词叫先行词。用来引导定语从句的词叫关系词（分为关系代词和关系副词）。定语从句一般放在先行词之后。如：ThisistheengineerwhowillgiveusatalAonscience.先行词关系词定语从句一、由关系代词引导的定语从句英语中的关系代词有who,whom,whose,which,that和as。它们的用法如下：1.who，whom的用法who和whom指人，在从句中分别作主语、宾语。作动词宾语时常被省掉。在口语中可用who代替whom。TheyoungworAerwhoinventedthistoolisherbrother.Thisistheboy(whom)Ihelped.2.which的用法which指物，在从句中作主语或宾语，作宾语是在非正式语体中可以省略。如：Thefactorywhichproducesthesecarsisverylarge.ThisisthebooA(which)youwant.3.whose的用法whose指人或物，在从句中作定语，不可省略。Whose有时可用ofwhich替换。如：Doyouliveintheroomwhosewindowopenstothewest?Thisisthestudentwhosepronunciationisthebestinourclass.4.that的用法that既可指人，也可指物，在从句中作主语或宾语。作宾语时，在非正式语体中常省略。如：TherewereoncesiGblindmenthat/wholivedinavillageinIndia.Wheatisaplantthat/whichisgrowninthenorthofChina.Theletter(that)Ireceivedwasfrommyfather.[注意]只能用关系代词that的场合that既可以指人也可以指物，但在下列场合，要用that，而不用which或who。1.先行词是不定代词all，anything，everything，nothing，much，little，few，any等时，只能用that。如：That’sallthatIwanttosay.Everythingthattheparentsdoisforthegoodoftheirchildren.2.先行词被all，any，no，theonly，thevery（恰好），little，few等词修饰时。如：ThanAyouforgivingmetheverybooAthatI’mlooAingfor.Heistheonlypersonthatwaspresentatthemeeting.IhavereadallthebooAs(that)yougaveme.3.指物的先行词被形容词的最高级或被序数词修饰时。如：Thisisthebestfilmthathasbeenshownthisyear.IliAethesecondfootballmatchthatwasheldlastweeA.4.先行词中既有人又有物时。如：Theherohassavedthehorseanditsriderthatfellintotheriver.HetalAedabouttheschoolandtheteachersthathehadvisited.5.当先行词为theway，thetime，theperiod等时，但that通常被省略。如：Idon’tliAetheway(that)youspeaAtoher.Thisisthelasttime(that)Ishallhelpyou.6.在which或who引导的特殊疑问句中，为避免重复用that引导取代which或who。用which不用that的情况1.在引导非限定性定语从句时。(错)Thetree,thatisfourhundredyearsold,isveryfamoushere.2.先行词指物，且介词后Wedependonthelandfromwhichwegetourfood.Wedependonthelandthat/whichwegetourfoodfrom.3.先行词本身是that时Idon’tthatwhichhedid.二、关系副词引导的定语从句英语中的关系副词有when，where，why等。在定语从句中充当状语，一般不可省略。1.when的用法when指时间、修饰表示时间的先行词，在定语从句中作时间状语，相当于at/in/onwhich。如：HowcanIforgetthedaywhen(=onwhich)IjoinedtheYouthLeague?Ithoughtofthedayswhen(=inwhich)westudiedtogether.Hecameatatimewhenthestudentsneededhim.2.where的用法where指地点，修饰表示地点的先行词，在定语从句中作地点状语，相当于in/on/atwhich。如：Thisisthefarmwhere(=onwhich)mygrandfatheronceworAed.Thatistheplacewhere(=inwhich)welivedtwoyearsago.3.why的用法why指原因，修饰名词reason，在定语从句中作原因状语，相当于forwhich。如：Idon’tAnowthereasonwhy(=forwhich)yougetsoangrywithme.DoyouAnowthereasonwhyhewaslateforschool?[注意]表示时间、地点的名词后关系词的选用当先行词是表示时间、地点的名词时，有时用when/where，有时用that/which引导定语从句。这时要根据从句的谓语动词是及物的还是不及物的而定。如果是及物动词就用that/which（作从句的主语或宾语）；如果是不及物动词，就用when/where（作从句的状语。）试比较：Thisisthehousewhere...