没有分别等于什么,具体句子具体对待
比如The room in which I was born remains the same.这里=where
The day on which I was born is unknown.这里 on which= when
The year in which i was born is unknown.这里in which=when
介词选择根据前面名词,或者后面动词来确定,而关系副词when,where根据前面是时间,还是地点来确定.
你问这个问题,说明你定语从句基本不懂,建议你找点详细资料,好好学学.