关系代词在定语从句中作介词宾语时，从句常常由“介词+关系代词”引出。

　　The school (which/that) he once studied in is very famous.

　　The school in which he once studied is very famous. 他曾经就读过的学校很出名。

　　Tomorrow I'll bring here the magazine (which/that) you asked for.

　　Tomorrow I'll bring here the magazine for which you asked.明天我将把你要的杂志带来。

　　This is the boy (whom/who/that) I played tennis with yesterday.

　　This is the boy with whom I played tennis yesterday. 这是我昨天跟他打台球的男孩。

　　We'll go to hear the famous singer (whom/who/that) we have often talked about.

　　We'll go to hear the famous singer about whom we have often talked. 我们将去听那位我们经常谈论的著名歌唱家演唱。

　　注意：

　　1.含有介词的短语动词一般不拆开，介词仍放在短语动词的后面。如：look for, look after, take care of 等。

　　This is the watch (which/that) I am looking for.(正) 这是我正在找的手表。

　　This is the watch for which I am looking .(误)

　　The babies (whom/who/that) the nurse is looking after are very healthy.(正)那个保姆照看的小宝宝们都很健康。

　　The babies after whom the nurse is looking are very healthy.(误)

　　2.若介词放在关系代词前，关系代词指人时只可用whom，不可用who, that;关系代词指物时只可用which，不可用that.关系代词是所有格时用whose.

　　The man with whom you talked just now is my neighbour.(正) 你刚才跟他谈话的那个人是我的邻居。

　　The man with that / who you talked just now is my neighbour.(误)

　　The plane in which we flew to Canada was really comfortable.(正)我们去加拿大所乘坐的飞机实在很舒服。

　　The plane in that we flew to Canada was really comfortable.(误)

　　3.“介词+关系代词”前还可有some, any, none, all, both, neither, many, most, each, few等代词或者数词。

　　如：He loves his parents deeply, both of whom are very kind to him.

　　他深深地爱着他的父母，他们俩待他都很好。。

　　In the basket there are quite many apples, some of which have gone bad.

　　篮子里有好些苹果，有些已经坏了。

　　There are forty students in our class in all, most of whom are from big cities.

　　我们班总共有40个学生，大多数来自大城市。

　　Up to now, he has written ten stories, three of which are about country life. 迄今为止，他写了10部小说，其中3部是关于农村生活的。