that和which关系代词的基本用法及特殊用法
在定语从句中，which 和that 在指代事物时，一般可以互换使用，但并非在任何情况下都是这样，这里介绍宜用that, 而不宜用which 的情况.
（1）先行词为不定代词（all, much, something除外）如everything, anything, nothing, none, the one等。
We should do all that is useful to the people .
我们应该做一切对人民有用的事。
There's nothing that can be said about it .
没什么可以说的了。
Do you mean the one that was bought yesterday?
你是说昨天买的那个吗？
（2）先行词被only, any, few, little, no, just, very, one of等词修饰时。
The only thing that we could do was to wait.
我们唯一能做的就是等待。
That's the very word that is wrongly used.
这就是那个错误使用的词。
比较 *This is one of the best novels that were published last year.这是去年出版的最好的小说之一。
*This is the only one of the best novels that was published last year.
这是去年出版的唯一一本最好的小说。
（3）先行词是序数词时或被序数词修饰时。
When we talk about Wuxi, the first that comes into mind is Tai Lake.
当我们谈论无锡时，首先想到的是太湖。
This is the third film that has been shown in our school this term.
这是本学期在我们学校展出的第三部电影。
（4）先行词是最高级或被最高级修饰时。
This is the best that can be done now.
这是现在可以做的最好的事情。
The most important thing that should be done right now is how to stop him from going on.
现在应该做的最重要的事情是如何阻止他继续前进。
（5）先行词既有人又有物，用which和who都不适合，这时宜用that. 如：
The writer and his novel that you have just talked about is really well known .
你刚才谈到的那位作家和他的小说真是广为人知。
The rider and his bike that had run over an old woman were held up by the police.
撞到老妇人的骑车人和他的自行车被警察拘留了。
（6）被修饰词为数词时.
Yesterday I caught two fish and put them in a basin of water . Now you can see the two that are still alive .
昨天我捉了两条鱼，把它们放在一盆水里。现在你可以看到那两个还活着。
（7）如果有两个从句，其中一个关系代词已用which ,另一个关系代词宜用that，以避免语言的单调或重复。
Edison built up a factory which produced things that had never been seen before.
爱迪生建立了一个工厂，生产以前从未见过的东西。
（8）疑问词是who或which，关系代词宜用that，以避免重复。
Which is the book that you like best?
你最喜欢哪本书？
Who is the man that is standing at the gate?
站在大门口的那个人是谁？
（9）主句是There be 结构，修饰其主句的定语从句宜用that 作关系代词. 如：
There is still a seat in the corner that is still free.
角落里还有一个座位，仍然是免费的。
（10）被修饰成分为表语时，或者关系代词本身是定语从句的表语时,该关系代词宜用that .
That's a good book that will help you a lot.
那本好书对你有很大帮助。
My home village is no longer the place ( that ) it used to be .
我的家乡已不再是过去的那个地方了。
