先要明白什么是先行词.被定语从句所修饰的中心词叫先行词.引导词在定于从句中代替的就是先行词.要想判断用什么引导词要先判断“先行词”即“引导词”放在定语从句中充当什么成分.which 是关系代词,where是关系副词.which在定于从句中主要可充当主语、宾语、表语.而where在定语从句中充当地点状语.但where 可以用"介词+which "来替换.具体which前用什么介词,要根据先行词放在定语从句中作地点状语前面应加什么介词而定.
eg.I remember that hospital forever where/ in which my daughter was born.( in hospital )