当关系代词在定语从句中作介词宾语时，我们通常用“介词＋关系代词”引导定语从句。
指“人”，用“介词＋whom”。指“物”，用“介词＋which”。
英语介词更准确应是前置词，表示名词，代词等与句中其它词的关系，在句中不能单独作句子成分。介词后面一般有名词，代词或相当于名词的其他词类、短语或从句作它的宾语，表示与其他成分的关系。
关系代词指的是代表先行词，同时在从句中作一定的句子成分。关系代词有主格，宾格和属格之分，并有指人与指物之分。关系代词用来引导定语从句。
介词加关系代词什么时候用
当关系代词在定语从句中作介词宾语时，我们通常用“介词＋关系代词”引导定语从句。
指“人”，用“介词＋whom”。指“物”，用“介词＋which”。
英语介词更准确应是前置词，表示名词，代词等与句中其它词的关系，在句中不能单独作句子成分。介词后面一般有名词，代词或相当于名词的其他词类、短语或从句作它的宾语，表示与其他成分的关系。
关系代词指的是代表先行词，同时在从句中作一定的句子成分。关系代词有主格，宾格和属格之分，并有指人与指物之分。关系代词用来引导定语从句。
介词加关系代词的三种情况是什么？
1、介词是跟动词搭配，动词往往不及物，或动词短语带有介词。这种情况一定要注意短语动词 look for，run into 之类的，整个视为一个单词，在句中不能拆开使用。
This is a problem most of us are likely to run into。
这是我们大多数人都可能遇到的问题。
2、介词跟形容词搭配使用。
Every student should do the assigned tasks for which they are responsible independently。(be responsible for)
每个学生都应该独立完成分配给他们的任务。(负责)
3、介词跟在名词后面
He had a wonderful chilhood，about which he wrote many stories。(stories about )
他有一个奇妙的童年，为此他写了许多故事。(关于的故事)
4、状语是一个介词短语
The professor wrote for him a letter of recommendation with which he applied for a position in that company。
教授为他写了一封推荐信，他随信申请了那家公司的一个职位。
扩展资料：
关系代词的用法关系代词在定语从句中做主语，宾语，表语，定语等。常用的关系代词有who，whom，whose，that，which，as等关系代词有三个作用：代替先行词；在定语从句中做句子成分；连接先行词与定语从句Thisisanoldcomputer。
关系代词指的是代表先行词，同时在从句中作一定的句子成分。关系代词有主格、宾格和属格之分，并有指人与指物之分。关系代词用来引导定语从句。
介词加关系代词怎么用?
介词+关系代词引导的定语从句关系代词在定语从句中做介词宾语时
从句常由介词+关系代词引导
(1) The school (that/which) he once studied in is very famous.
(2) The school in which he once studied is very famous.
(3) Tomorrow I will bring here a magazine (that/which) you asked for.
(4) Tomorrow I will bring here a magazine for which you asked.
(5) We’ll go to hear the famous singer (whom/that/who) we have often talked about.
(6) We’ll go to hear the famous singer about whom we have often talked.
注意：1. 含有介词的动词短语一般不拆开使用,如：look for, look after, take care of等
(1) This is the watch which/that I am looking for. (T＝正确)
(2) This is the watch for which I am looking. (F＝错误)
2. 若介词放在关系代词前,关系代词指人时用whom,不可用who或者that；指物时用which,不能用that；关系代词是所有格时用whose
(1) The man with whom you talked is my friend. (T)
(2) The man with that you talked is my friend. (F)
(3) The plane in which we flew to Canada is very comfortable. (T)
(4) The plane in that we flew in to Canada is very comfortable. (F)
3. “介词+关系代词”前可有some, any, none, both, all, neither, most, each, few等代词或者数词
(1) He loved his parents deeply, both of whom are very kind to him.
(2) In the basket there are quite many apples, some of which have gone bad.
(3) There are forty students in our class in all, most of whom are from big cities.
介词加关系代词怎么用？
“介词＋关系代词”在从句中主要起关系副词的作用，即在定语从句中充当状语。
表示地点，时间和原因的“介词＋which”分别相当于where，when，why。I have found the book in which thenames of all the early satellites are mentioned．（SEFC 2A L．55）（＝Ihave found the book．The names of all the early satellites arementioned in it．）The earth on which ／where we live is aplanet．
way后常用that代替in which，也可省略that。I really don't like the way that hetalks．That was the way in which the old ladylooked after us．Do it the way I showed you．
“of＋which”起形容词的作用，相当于whose（用来指物），其词序通常是“n．＋of which”。They live in a house whose door ／thedoor of which opens to the south.He's written a book whose name ／thename of which I've com- pletely forgotten．
英语:定语从句中什么时候用介词加关系代词
当从句中不少主语或宾语，而缺少状语时，要用介词加关系代词。如：
I
will
never
forget
the
day
(on
which)
I
came
here.
从句中I
came
here
不少主语，也不用宾语。因为与某一天有关，护海篙剿蕻济戈汐恭搂所以用on
加
which。句中的on
which
可以用when
换，用来表时间。
定语从句中何时使用“介词＋关系代词”？何时不用？
有两种情况:
1.当你要用where
when之类的特殊关系代词时,就要用到介词.如:why=for
which,where=in
which,when=during
which,whose=of
which等.不过具体用什么介词,就要看你句子的需要啦~
2.当你要用一些不及物动词的时候,这些动词后面往往要用介词来连接后面的宾语.这时,可以将这些介词放到关系代词前面.这不就构成了介词+关系代词的结构咯~
英语介词+关系代词的用法.
(1)介词放在句末时,who,that,which可省
但介词在关系代词前时,只能用“介词+which/whom”结构.例如：
This is the house to which we lived last year.
=This is the house which we lived last year to
Please tell me to whom you borrowed the English novel
=Please tell me whom you borrowed the English novel to
(2).含有介词的固定动词词组中,介词不可前置,只能放在原来的位置上.
This is the person whom you are looking for.这就是你要找的那个人.
定语从句中什么时候用介词加关系副词，什么时候用介词加关系代词？
同位语意思完整的用that
引导，不完整时用whether
when
where
how
等引导，定语从句that
既代替先行词同时又在从句中作成分（主语或宾语），而同位语中的that
是连词，只起连接主句与从句的作用，不充当句中任何成分。介词加关系代词等于关系副词，介词加关系副词是因为动词为不及物动词需加介词
