同学你好，该知识点来自沪江网校《新概念英语第三册【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好：
关于“介词+引导词”引导定语从句的情况，包括：

1 “介词 + 关系代词”引导定语从句时，介词的宾语只能用which（指物）和whom（指人），即：介词+which/whom。不能用that 和who。
This is the teacher from whom we’ve learned a lot.
这就是从他那里我们学了很多东西的老师。
Great changes have taken place in the city in which we live.
我们所居住的城市发生了巨大的变化。

2 有时介词也可放在从句的末尾，这时关系代词可用which/that(指物)，who/whom/that（指人），也可以省略。
The situation (which/that ) we had got into was very dangerous.
我们当时的处境很危险。  
The man (whom/who/that) you were talking to just now is my English teacher.
你刚刚和他谈话的那个人是我的英语老师。

3 当定语从句中的谓语动词短语是固定搭配，不可分割时，那么动词短语中的介词不能前置。
This is the pen which I’m looking for. 这是我正在找的那支钢笔。    
不能写成：This is the pen for which I’m looking.

4 定语从句也可由“名词/代词/数词+介词+which/whom”引出。
That old man has two sons, one of whom is a doctor.
那个老人有两个儿子，其中一个是医生。  
The house, the windows of which ( = whose windows = of which the windows) were damaged, has now been repaired. 窗子遭破坏的那栋房子现在已经修好了。

5 引导定语从句的关系副词(when, where, why) 可以用“介词+关系代词”代替。
I’ll never forget the day when I joined the party. (when= on which).
我永远都不会忘记入党的日子。
The factory where my father works is in the east of the city. (where = in which).
父亲工作的那家工厂在城东。
None of us know the reason why Tom was absent from the meeting. (why = for which).
我们都不知道汤姆缺席会议的原因。

6 “复合介词短语+which”引导的定语从句，常与先行词用逗号隔开，而且定语从句常用倒装语序。
He lived in a big house, in front of which stood a big tall tree.  
他住在一幢大房子里，房前有一棵大树。

祝学习愉快！