如果从句中缺少状语,则用介词+which 其实就相当于where和when的效果 .
which前的介词跟定语从句修饰的内容有关,被修饰的内容与什么介词搭配,which前就用什么介词,如He choose the way in which he can finish his work better.因为way和in才能搭配,故which前用in ; ...看先行词需要什么介词搭配,例如先行词是school,那就是缺at,因为是at school额 懂一些..但像 The pen ____he is writing is mine 这个应该是with which 还是in which.......等呢？是with。 因为你可以把定语从句还原成完整的句子He is writing with my pen.