on which和in which都可用在定语从句中引导定语从句，修饰先行词。区别在于介词On/in，这取决于先行词的搭配。in which侧重于表示一种所属关系。on which侧重于表示一种目的关系。

on which 与in which 的区别有哪些

on which 和 in which 在英语中都可以用来引导定语从句，修饰先行词，但它们的用法和侧重点有所不同：

1、on which 通常表示“在哪个位置”或者“在哪个时间”。例如：

The meeting will be held on Friday, on which we will discuss the new project.（会议将在星期五举行，届时我们将讨论新项目。）

The hotel, on which we stayed last year, was very comfortable.（我们去年住的酒店，on which引导的定语从句，非常舒适。）

2、on which 还可以用来引导定语从句，用来描述前面所提到的事物。这种用法在日常英语中非常常见。

3、in which 则更多地用来表示“在哪个场合”或者“在哪个情况下”。例如：

The situation, in which we found ourselves, was very dangerous.（我们发现自己处于的情境非常危险。）

The party, in which we participated last week, was a great success.（我们参与的派对非常成功。）

4、in which 也可以用来引导定语从句，用来描述前面所提到的事物。

总结来说，on which 和 in which 都可以用来引导定语从句，但 on which 更多地用于描述位置或时间，而 in which 则更多地用于描述场合或情况。

如何判断which前加什么介词

一考查定语从句中谓语动词的搭配习惯

(1)看定语从句中动词与介词的搭配Water is the natural medium in which fish live.(注意搭配live in)

后面的句子中的动词或动词短语如果必须要加介词才能加宾语的时候 ,先行词在从句中做宾语时,动词或者动词短后的介词可以提前 构成 介词+关系代词 的结果

注：有一些介词为固定搭配的一部分,此时它们的位置应注意.如stay in ,look at 等,像 look for ,give up 这种短语是不能把介词提前的.

(2)看定语从句中形容词与介词的搭配

He referred me to some reference books with which I am not very familiar.

他要我去参考一些我不熟悉的参考书.(注意搭配be familiar with)

二考查先行词与介词的搭配习惯

这类考题往往要根据具体的语境来选择介词.如：I’ll never forget the day on which she said goodbye to me.(注意搭配on the day)

三考查表示所属关系的of which

On the blackboard the teacher wrote a sentence,the meaning of which I don’t understand. 老师在黑板上写了一个句子,句子的意思我不明白.(注意搭配the meaning of the sentence)

四考查表示整体与部分关系的of which

The buses,most of which were already full,were surrounded by an angry crowd. 多数公共汽车已经上满了人,周围是一伙愤怒的群众.(注意搭most of the buses)

五考查表示同位关系的of which

Her sons,both of whom work abroad,rang her up this morning. 她的两个儿子都在国外工作,今天早上给她打了电话.(注意搭配both of her sons