“介词＋关系代词”,无非就是代替先行词的关系代词在从句中担任"介词宾语".正确使用就要了解这个介词是根据什么来定的.

　　1.　介词是跟动词搭配,动词往往不及物,或动词短语带有介词.

　　Ivisitedthecityinwhichmyfatherhadworkedfor10years.(workinthecity)

　　　Thisisaveryimportantproblemtowhichweallshouldpayattention.(payattentiontotheproblem)

　　这种情况一定要注意短语动词　lookfor,runinto之类的,整个视为一个单词,在句中不能拆开使用.

　　Thisisaproblemmostofusarelikelytoruninto.

　　Itistherightbookthatshewaslookingfor.

　　2.介词跟形容词搭配使用.

　　Everystudentshoulddotheassignedtasksforwhichtheyareresponsibleindependently.(beresponsiblefor)

　　3.介词跟在名词后面

　　Hehadawonderfulchilhood,aboutwhichhewrotemanystories.(storiesabout)

　　4.状语是一个介词短语

　　Theprofessorwroteforhimaletterofrecommendationwithwhichheappliedforapositioninthatcompany.