定语从句1、功能：=形容词，修饰名词或代词，在句中作定语一：先行词：被定语从句所修饰的词二：关系词：用来连接定语从句，并在从句中代表先行词。在从句中充当的成分：主语、宾语学会找关系词，看先行词指的是什么-----先行词，看关系词在从句中所充当的成分。2、一般用法先行词是物：whichthat先行词是人：whowhomthat关系代词在从句中作宾语时可以省略。e.g.Theyoungman(whom)yousawwasourmanager.Thereissomething(that)wemustkeepinmind.限制性定语从句与非限制性定语从句（逗号隔开非限制）限制性定语从句：从句与主句关系密切，去掉从句，主句意义不完整，甚至不合逻辑。e.g.Iwastheonlypersoninourofficewhowasinvited.（去掉定语从句，意思就不完整）非限制性定语从句：从句对先行词关系不密切，去掉定从句，意思仍然完整。形式上用逗号隔开，不能that用引导。e.g.Tom’sfather,whoisoversixty,stillworksharddayandnight.that与which的区别1）用that而不用which的情况①先行词为不定代词all,anything,nothing,…；②先行词有最高级修饰，有序数词修饰；③先行词有only,very,any等词修饰；④先行词既有人又有物时。2）用which而不用that的情况：①引导非限制性定语从句；②指代前面整个主句的意思；③介词+关系代词。3、whose的用法关系代词与其后的名词构成所有格，即“的”时，它既可以修饰指人的先行词，也可以修饰指物的先行词。e.g.1.Thegirlismydaughter.Herworkgotthefirstprize.Thegirlwhoseworkgotthefirstprizeismydaughter.4、介宾结构关系代词在从句中作介词的宾语时，介词可以提前，但关系代词只能用which（物）或whom（人）。e.g.1.Themanisafamousrunner.Youtalkedtohimjustnow.Themantowhomyoutalkjustnowisafamousrunner.2.Thechairismadeofwood.Heissittingonitnow.Thechaironwhichheissittingnowismadeofwood.3.Heisalibraryassistant.Iborrowedsomebooksfromhim.HeisalibraryassistantfromwhomIborrowedsomebooks.4.Itisafamousschool.Hegraduatedfromit3yearsago.ItisafamousschoolfromwhichHegraduated3yearsago.有一些动词短语中的介词是固定搭配，不可以拆开。(lookaftertakecareoflookfor)e.g.Heisthestudentwhotheteachersarelookingfor.Thenumberofthechildrenwhoshetakescareofis30.5、关系副词：whenwherewhy=介词+which先行词：时间——>when=onwhich从句：时间状语地点——>where=in/atwhich地点状语原因——>why=forwhich原因状语判断把先行词放回从句中（关系词）作什么成分：作状语用whenwhere和why，否则用前面所述。e.g.1.Iwillneverforgettheday./Iwenttouniversityonthatday.Iwillneverforgetthedaywhen/onwhichIwenttouniversity.2.Thisisthehouse./Heusedtoliveinthehouse.Thisisthehousewhere/inwhichheusedtolive.3.Idon’tknowthereason./Hediditforthisreason.Idon’tknowthereasonwhy/forwhichhedidit.①一般用法1.Tomisgoodatmaths,soIthinkheisthestudent______canhelpyoutoworkoutthisproblem.A．whomB．whoC．whichD．what2.I’mnotsurewhetherthisisthe