如果which或whom在定语从句中作介词宾语,那么该介词可以置于从句前,这种定语从句修饰人时,介词后只用whom,修饰物时只用which,不能用that,因为介词后接that意思发生改变,如in+that=because引导原因状语从句,另外介词+which还可等同于关系副词,如in/on, at+which=when/w...