介词+which引导的定语从句

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答：是介词+关系代词引导定语从句。

The ease with which people can change from working in the day to working at night is a matter growing importance in industry.

句意：人们可以轻松地从白天工作转变为晚上工作，这在工业中是一个日益重要的问题。

定语从句的本质是两个句子合并成一个句子，前提是两个句子中存在一个重合的名词。

根据这个原理，我们把上面这个句子拆分成两个句子：

① The ease is a matter growing importance in industry.

在工业界，轻松是一个越来越重要的问题。

② People can change from working in the day to working at night with ease.

人们可以轻松地从白天工作变成晚上工作。

我们发现，句子①和句子②存在的重叠名词是ease “容易，舒适，自由自在”。

当我们把两个句子合并成一个句子的时候，重叠的名词用关系词取代。

当被修饰的名词表示事物，且在定语从句中作宾语的时候，用that/which。

而当介词和宾语一块提前时候，只能用which。

因此，我们把句子①和句子②合并成一个含有定语从句的主从复合句之后，就写成了这个样子：

The ease 【with which people can change from working in the day to working at night】 is a matter growing importance in industry.

The ease 是句子的主语，with which people can change from working in the day to working at night  是介词＋关系代词引导的定语从句。

更多介词+关系代词引导定语从句的例子：

1. I will never forget the day on which I joined the army.

拆分成两个句子：

① I will never forget the day.

② I joined the army on the day.

合并：

I will never forget the day on which I joined the army.  

（重叠的名词被which取代，介词是on）

我永远不会忘记我参军的那一天。

2. Have you found the book for which I paid 29 dollars?

拆分成两个句子：

① Have you found the book?

② I paid 29 dollars for the book.

合并：

Have you found the book for which I paid 29 dollars? 

（重叠的名词被which取代，介词是for)

你找到我花29美元买的那本书了吗？

3. I'll never forget the way in which my teacher taught me.

拆分成两个句子：

① I'll never forget the way.

② My teacher taught me in the day.

合并：

I'll never forget the way in which my teacher taught me.

（重叠的名词被which取代，介词是in)

我永远不会忘记老师教我的方式。

总结：

介词如何选？拆分成两个句子后，看和重叠的名词如何搭配再决定。