介詞+關系代詞引導的定語從句

在介詞后作賓語的關系代詞只有 which?和 whom。如先行詞是物，引導詞用 which；如先行詞是人，則引導詞用whom。

一、看從句的動詞選介詞：所用介詞需與定語從句中的動詞構成固定搭配
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、看從句的形容詞選介詞：所用介詞需與定語從句中的形容詞構成固定搭配
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、看從句的名詞選介詞：所用介詞需與定語從句中的名詞構成固定搭配
例句5：I am sending you an inquiry, to which your prompt attention is highly appreciated.

四、看先行詞選介詞
這類情況，關系代詞前面用什么介詞與定語從句沒有關系，而是與關系代詞前面的先行詞緊密相關，所選用的介詞要與先行詞構成固定搭配。
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.

要想正確地使用介詞，我們必須記住相關的介詞短語搭配。常見的有：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。