1.who指人,在从句中做主语 　　(1)TheboyswhoareplayingfootballarefromClassOne. 　　(2)YesterdayIhelpedanoldmanwholosthisway. 　　2.whom指人,在定语从句中充当宾语,常可省略. 　　(1)Mr.Liuistheperson(whom)youtalkedaboutonthebus. 　　(2)Mr.LingisjusttheboywhomIwanttosee. 　　注意：关系代词whom在口语和非正式语体中常用who代替,可省略. 　　如果在从句中做宾语,就用whom或who.比如:Heisthemanwhom/whoItalkto. 　　如果是在从句中作主语就只能用who.比如:HeisthemanwhohasanEnglishbook. 　　(3)Themanwho/whomyoumetjustnowismyfriend 　　3.which指物,在定语从句中做主语或者宾语,做宾语时可省略 　　(1)Footballisagamewhichislikedbymostboys. 　　(2)Thisisthepen(which)heboughtyesterday. 　　4.that指人时,相当于who或者whom；指物时,相当于which. 　　在定语从句中做主语或者宾语,做宾语时可省略. 　　(5)Thenumberofthepeoplethat/whocometovisitthecityeachyearrisesonemillion. 　　(6)Whereisthemanthat/whomIsawthismorning? 　　5.whose通常指人,也可指物,在定语从句中做定语 　　(1)Hehasafriendwhosefatherisadoctor. 　　(2)Ioncelivedinahousewhoseroofhasfallenin.whose指物时,常用以下结构来代替 　　(3)Theclassroomwhosedoorisbrokenwillsoonberepaired. 　　(4)Theclassroomthedoorofwhichisbrokenwillsoonberepaired. 　　(5)Doyoulikethebookwhosecolorisyellow? 　　(6)Doyoulikethebookthecolorofwhichisyellow? 　　1.when指时间,在定语从句中做时间状语 　　(1)IstillrememberthedaywhenIfirstcametotheschool. 　　(2)Thetimewhenwegottogetherfinallycame. 　　2.where指地点,在定语从句中做地点状语 　　(1)ShanghaiisthecitywhereIwasborn. 　　(2)ThehousewhereIlivedtenyearsagohasbeenpulleddown. 　　3.why指原因,在定语从句中做原因状语 　　(1)Pleasetellmethereasonwhyyoumissedtheplane. 　　(2)Idon’tknowthereasonwhyhelooksunhappytoday. 　　注意：关系副词引导的从句可以由“介词+关系代词”引导的从句替换 　　(1)Thereasonwhy/forwhichherefusedtheinvitationisnotclear, 　　(2)Fromtheyearwhen/inwhichhewasgoingtoschoolhebegantoknowwhathewantedwhenhegrewup. 　　(3)Greatchangeshavetakenplaceinthecityinwhich./whereIwasborn.