定语从句关系词that和which的区别

定语从句在句中做定语，修饰名词或代词，被修饰的词即“先行词”。定语从句位于先行词之后，由“关系词”（关系代词或关系副词）引出。关系代词有：who, whom, whose, that, which等。关系副词有：when, where, why等。

关系代词只能用that的地方:

1. 先行词既有人又有物

例 The person and the dog (that) we met the other day were unforgettable.

2. 先行词为something, everything, anything, nothing, none; all, some, any等不定代词，或先行词前有some, every, any, no, all, much, few, little(少量的)等修饰时

例 All that glitters is not gold.

例 There is something (that) I need to tell you.

例 I have many books. Take all/some/any that might be helpful to you.

3. 先行词前有序数词或形容词最高级修饰时

例 The first thing that came to mind is his dignity.

例 The best thing that ever happened to me happened yesterday.

只用which的地方：

1. 非限制性定语从句（即逗号后面）

例 The house, which we bought last month, is very nice.

2. 介词之后

例 We depend on the land from which we get our food. = We depend on the land (that/which) we get our food from.