表代替

　　1) This is the book which you want to read. (这是你要阅读的书。---- 关系代词which作定语从句to read的宾语。在这种情况下，可以省去关系代词：This is the book you want to read.)

　　2) This is the book about which you have talked to me. (这是你曾经给我谈起的那本书。---- 关系代词which在定语从句中作介词about的宾语，which的先行词只是前面的the book。当引导定语从句的关系代词前面有介词时，只能用关系代词which。在口语中，一般喜欢把介词放到定语从句的后面去, 同时省略掉关系代词which：This is the book you have talked about to me. 这就是你所问的那种情况。)

　　3) This is the book on the cover of which there is a map of China. (这是封面上有张中国地图的那本书。---- 关系代词前面不是一个介词，而是一个介词词组，这时也只能用关系代词which，不能用that。和上面例句不同的是：不能将这个介词词组放到定语从句的后面去，我们一般不能说：This is the book there is a map of China on the cover of .)