in which , for which ,on whch ,at which d的不同用法

in which , for which ,on whch ,at which d的不同用法

这些都是定语从句里面，由which引导的定语从句，介词提前。
in which 可以翻译成在......里面
for which 可以翻译成为了......目的
on whch 可以翻译成在......的上面
at which 可以翻译成在.....里面或在.....上面
这些介词的使用除了意思上的区别，具体是要以which引导的从句而定的
例如 (1) The school (that/which) he once studied in is very famous."
　　= The school in which he once studied is very famous.　
(2) Tomorrow I will bring here a magazine (that/which) you asked for. 　　
= Tomorrow I will bring here a magazine for which you asked. 　　
(3) I have a dresser in my bedroom, which there are many cosmetics on.
= I have a dresser in my bedroom on which there are many cosmetics.
（4 ) The dumpling House which he often has dumplings at is very popular.
= The dumpling House is very popular, at which he often has dumplings.
当然这只是介词作为基本意思的用法，还有一些固定搭配，得具体情况具体分析。
例如 The plane may be several hours late,in which case there's no point in our waiting.
（固定搭配：in the case)
The speaker paused to examine his notes,at which point a loud crash was heard.
( 固定搭配：at the point)
Ten years of hard work changed her greatly,for which reason he could hardly recognize her at first sight. (固定搭配：for the reason)

in which 大多后面接的是地点，属于地点状语从句的引导词。
for which后面接原因，是原因状语从句。
on which一般也可以接地点，但是只是表面，比如墙的表面就可以用on which。which代指后面接的词语。
at whichy大多接时间，比如几点钟，属于时间状语从句的用法。

这些都是定语从句里面，由which引导的定语从句，介词提前。
in which 可以翻译成在......里面 指地点是大地点 指时间 就是原来该用in 地方
for which 可以翻译成为了......目的
on whch 可以翻译成在......的上面 指时间是指具体某天
at which 可以翻译成在.....里面或在.....上面