“介词+ which / whom”引导的定语从句
“介词+关系代词”引导的定语从句，是定语从句一种介词前置的定语从句句型，介词与关系代词之间存在一种介宾关系。当关系代词在定语从句中作介词宾语时，把介词置于关系代词前，即演变出“介词+关系代词”句型。例如：
The man who/whom /that you spoke to is a teacher.
=The man to whom you spoke is a teacher.
一、基本构成
1.“介词+关系代词”结构引导的定语从句中，关系代词只能用which（指物）或whom(指人) ，即：介词+which/whom。
（1）The man to whom you spoke is a teacher.
（2）The city in which she lives is far away.
（3）The little girl is reading a book,in which there are many cartoons.
注意：当介词放在关系代词的前面时，用在介词后的关系代词不能省略。
2.在限制性定语从句中，当介词置于定语从句的谓语动词之后时，可用that/which(指物)；that/who/whom（指人）作介词的宾语.且此处关系代词可以省略，特别是在口语中。如：（1) The man (who/whom /that )you spoke to is a teacher.
（2）The city（which/that）she lives in is far away.
注：通常介词放在定语从句中动词后，也可以放在关系代词前面，但有些特殊动词短语搭配不能拆分，介词只能放在动词后，如： look for, look after, pay attention to ,take care of , look forward to, listen to等。
This is the pen that / which you are looking for.
The patient whom she is looking after is her father.
The words that /which we should pay attention to are written on the blackboard.
There are fifty patients who/whom/that we must take good care of.
练习：Are these sentences right?
(1) The man with whom you talked is my friend.
(2) The man(who/that) you talked with is my friend.
(3) The man with who/that you talked is my friend.
(4) The plane in which we flew to Canada is very comfortable.
(5) The plane in that we flew to Canada is very comfortable.
二、关系副词when，where，why可用“介词＋which”来代替。关系副词实际上是介词＋先行词。
when=表时间的介词（如：in，at,during等）+which；
Where=表地点的介词（如：in，at,on,under等）+which；
Why=表原因的介词（如：for）+which
(1)当先行词表示时间，定语从句中缺少时间状语时，通常用关系副词when引导，此时也可选用表示时间的介词＋which来代替关系副词when。
I still remember the day when I came here. ( on the day =when)
(2)当先行词表示地点，定语从句中缺少地点状语时，通常用关系副词where引导，此时也可选用表示地点的介词＋which来代替关系副词where。
This is the house where I lived last year. ( in the house= where)
(3)当先行词为reason，定语从句中缺少表示原因状语时，通常用关系副词why引导，此时也可以用for which来代替关系副词why。
There are many reasons why people like traveling. (for the reasons =why)
三、关系代词前介词选择三原则：一先，二动，三意义（重中之重）
1.一先，即根据定语从句中介词与先行词的搭配关系选择。
I never forget the day on which I came to this school. (on the day)
2.二动，即根据定语从句中谓语动词与介词的搭配关系选择。
This is the iPad on which I spent 3000 yuan. (spend money on sth.)
3.三意义，即根据定语从句的意义来确定介词。
This is my pair of glasses, __without which__I cannot see clearly.
例题：用“介词+关系代词”的形式表示
1. Do you like the book __________ she learned a lot?
2. He paid the boy $10 for washing ten windows, most ______ hadn't been cleaned for at least
a year.
3. The tower _________ people can have a good view is on the hill.
注意：
介词+关系代词
1）介词后面的关系代词不能省略。
2）that前不能有介词。
3）某些在从句中充当时间，地点或原因状语的"介词+关系词"结构可以同关系副词when,where和why互换。
