关系副词、“介词 + which / whom”
例句：
1、 This is the village where / in which I ever lived.
2、 Can you tell me the office where / in which he works?
3、 I still remember the day when / on which I first came to Beijing.
4、 Do you know the reason why / for which he is absent?
5、 The woman with whom I talked just now comes from America.
6、 This is the book which she is looking for.
用法归纳：
1、 关系副词在定语从句中的基本用法：when作时间状语，where作地点状语，why作原因状语（先行词只有reason一词）在定语从句中，关系副词一般可转化为“介词 + which / whom”。
2、 “介词 + which / whom”中的介词，可置于从句之前，也可置于从句之后，但以置于从句之前较为正式。“介词 + which / whom”中只能用which指代物，用whom指代人。但含有介词的短语动词一般不拆开，介词仍放在动词的后面。
如：
The teacher from whom I learnt most was Mrs. Zhu.
The machine which I have looked after for twenty years is still working well
