介词+关系代词引导的定语从句

在介词后作宾语的关系代词只有 which 和 whom。如先行词是物，引导词用 which；如先行词是人，则引导词用whom。

一、看从句的动词选介词：所用介词需与定语从句中的动词构成固定搭配
例句1：The girl with whom you work is his girl friend.
例句2：The goals for which he had fought all his life no longer seemed important to him.

二、看从句的形容词选介词：所用介词需与定语从句中的形容词构成固定搭配
例句3：He referred me to some reference books with which I am not very familiar.
例句4：They will pass along their fresh impressions to the youth groups in which they are active.

三、看从句的名词选介词：所用介词需与定语从句中的名词构成固定搭配
例句5：I am sending you an inquiry, to which your prompt attention is highly appreciated.

四、看先行词选介词
这类情况，关系代词前面用什么介词与定语从句没有关系，而是与关系代词前面的先行词紧密相关，所选用的介词要与先行词构成固定搭配。
例句6：About a thousand species of animals are in danger of extinction, and the rate at which they are being destroyed has increased.

要想正确地使用介词，我们必须记住相关的介词短语搭配。常见的有：with ease，at the rate，in the direction，to the extent，to the degree，at the temperature，by the means，by the mode，in a culture，in practice 等等。