in which，for which，on which，at which有什么区别，怎么使用，用法

in which，for which，on which，at which有什么区别，怎么使用，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 which可以翻译成在„„的上面，或具体时间的某一天 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）
The film at which I fell asleep was very boring.
（Here "at which" is based on "fell asleep at the film"因为电影无聊而睡觉。） The little creature in which scientists are interested is known as ET. （这里"be interested in"是词组原因）
This is the book for which he is looking.
（即等于This is the book which he is looking for，这主要是因为look for 这一短语）

这都是定语从句，就是被修饰的名词是从句中的副词形式。如
a substance capable of reducing the surface tension of a liquid in which it isdissolved.
一种能减少溶解它的液体的表面张力的物质，这里which修饰液体，在这种液体中。
They had been used by the researchers for an experiment for which they hadnot consented.
他们在没有同意的情形下被研究者利用，这里which修饰experiment，对于这种实验来说。
This is the subject on which he made great progress.
这就是他取得巨大进步的科目。这里which修饰subject，在这个学科上。
Just a regular meeting, at which the company operation status and future planswill be reviewed.
只是一个例行会议，通报一下公司的营运状况和前景规划。这里which修饰会议，在这个会议上

in which, for which, on which, at which的不同用法
　　1)这些都是定语从句里面，由which引导的定语从句，介词提前。下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。
　　①in which可以翻译成在……里面
　　The school (that/which) he once studied in is very famous.
　　= The school in which he once studied is very famous.
　　②for which可以翻译成为了……目的
　　Tomorrow I will bring here a magazine (that/which) you asked for.
　　= Tomorrow I will bring here a magazine for which you asked.
　　③on which可以翻译成在……的上面，或具体时间的某一天
　　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.
　　④at which可以翻译成在……里面或在……
　　The dumpling House which he often has dumplings at is very popular.
　　= The dumpling House is very popular, at which he often has dumplings.
　　2)当然第一点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。
　　①The plane may be several hours late, in which case there’s no point in our waiting.
　　(固定搭配：in the case)
　　②The speaker paused to examine his notes, at which point a loud crash was heard.
　　(固定搭配：at the point)
　　③Ten 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)
　　④The film at which I fell asleep was very boring.
　　(Here "at which" is based on "fell asleep at the film"因为电影无聊而睡觉。)
　　⑤The little creature in which scientists are interested is known as ET.
　　(这里"be interested in"是词组原因)
　　⑥This is the book for which he is looking.
　　(即等于This is the book which he is looking for，这主要是因为look for 这一短语)