for which 是介词+which 引导定语从句的结构之一.
介词+which显然与which引导定语从句是不一样的.如:
The book in which there are many pictures is mine.这句话中,in which不能改为which.我们将定语从句还原:There are many pictures in the book.(in which= in the book)
又如:Mr.Li’s new house for which he paid ten thousand yuan was burnt down last night.将定语从句还原Mr.Li paid ten thousand yuan for his new house.(for which =for his new house )