定义、分类及相关术语关系词通常有下列三个作用：A.引导从句；（连词）B.代替先行词；（代词）C.在定语从句中担当一个成分。3.定语从句分类及区别1).a.Thereason_______hemissedthespeechisthatheforgotthetime.b.Thereason_____________hegaveussoundedreasonable.2).a.I’llneverforgettheday____________wespenttogetherinParis.b.I’llneverforgettheday________westayedtogetheratthattime.3).a.Isthisthefactory_______________wevisitedlastyear?b.Isthisthehouse_________Lincolnoncelived?c.Isthishouse_____wevisitedlastyear?A.whichB.whereC.theoneD.that介词+关系代词引导的定语从句2.根据先行词来选择介词。(介词和先行词之间构成习惯搭配，而和从句谓语动词没多大系，此时介词位于关系代词之前。)Hestoodbythewindow,throughwhichhecouldseewhatwashappeningoutside.3.介词+关系代词=关系副词（when,why,where）Thisisthehouseinwhich/whereChairmanMaooncelived.Everyoneknowsthereasonwhy/forwhichthehighdamwasbuilt.选择定语从句的引导词时，不能只看先行词，重要的是看引导词在从句中充当什么成分。1).Thisisthereason________________helefthishometown.2).I’llneverforgettheday_________________westayedtogether3).Thisisthegirl___________Ilearnedthenews.4).Thisisthegirl_____istakengoodcare___inthehospital.5).I’llshowyouastore________________youmaybuyallthatyouneed.6).Idon’tliketheway__________________youlaughedather.as与which的区别1.Which代替的先行词可以是名词，也可以是句子的一部分或整个句子；which从句不能放在句首;区别thesame…as与thesame…that1.当先行词是everything,anything,nothing,all,none,few,little,some等代词时，或当先行词受every,any,all,some,no,little,few,much等代词修饰时。1).a.Isawsometrees,andtheleavesof_______wereblackwithdisease.b.Isawsometrees,theleavesof______wereblackwithdisease.2).a.Theprofessorisalittleman,onthenoseof______thereisapairofglassesb.Theprofessorisalittleman,andonthenoseof______thereisapairofglasses1).a.Thenews________ourvolleyballteamwonthematchmadeusexcited.b.Thenews__________hetoldmeyesterdayisexciting.2).a.Imadeapromise______ifanyonesetmefree,Iwouldmakehimveryrich.b.Themothermadeapromise___________pleasedallherchildren.1)a.Itisinthisroom______Ilivedlastyear.b.Itistheroom_______Ilivedlastyear.2)a.Itwasatseveno’clock______hewenttoschoolthismorning.b.Itwasseveno’clock_______hewenttoschoolthismorning.Findt