先看几道考题，能做对就不用往下看了：
The world _____ we live is made up of matter．
A． on which B． of which C． at which D． in which
The dictionary _____ is sold out in the bookshop．
A． you need B． what you need C． which you need it D． that you need it
如果您对上面的问题还有疑惑，请仔细阅读本文。题目的答案及解析会在文章中逐步给出。
1、which引导限定性定语从句
先行词作主语：
A computer is a machine which can do many things for us.
电脑是一种可以为我们做许多事情的机器。
先行词作介词宾语：
The chair in which she sat is made of wood
她坐的椅子是用木头做的。( which作介词的宾语)
先行词表示地点，时间时，介词＋which分别相当于 where，when
The earth on which（where）we live is a planet.
我们居住的地球是一个行星。
This is the city in which（where） I lived.
这就是我居住的城市。
of ＋which作形容词，相当于whose
They live in a house whose door ／the door of which opens to the south.
他们住在一个门朝南的房子里。
2、which引导非限定性定语从句
Mo yan was awarded the nobelprize in literature , which made us happy
莫言被授子诺贝尔文学奖,这使我们非常高兴。
3、which引导名词性从句，which既作名词性从句的引导词，同时又是名词性从句的疑问词
Tell me which you like best.
Tell me which is your favorite color.
现在给出本文开始考题的答案：
The world _____ we live is made up of matter．
A． on which B． of which C． at which D． in which
答案：选D。介词in与live搭配，提到关系代词之前。
The dictionary _____ is sold out in the bookshop．
A． you need B． what you need C． which you need it D． that you need it
答案：选A。关系代词为that或者which， 在从句中作宾语，可以省略。
