关系代词that的用法
1）不用that的情况
a) 在引导
非限定性定语从句时。
(错) The tree, that is four hundred years old, is very famous here.
b) 介词后不能用。
We depend on the land from which we get our food.
We depend on the land that/which we get our food from.
2) 只能用that作为定语从句的关系代词的情况
a) 在
there be 句型中，只用that，不用which。
b) 在
不定代词，如：anything, nothing, the one, all, much, few, any, little等作
先行词时，只用that，不用which。
c) 先行词有the only, the very修饰时，只用that。
d) 先行词为
序数词、数词、形容词最高级时，只用that。.
e) 先行词既有人，又有物时。
举例：
All that is needed is a supply of oil.
所需的只是供油问题。
Finally, the thief handed everything that he had stolen to the police.
那贼最终把偷的全部东西交给了警察。
that可以在从句中作主语。
关系代词that。
关系代词that在从句中可作主语、宾语、
表语。作宾语时，that可省略。它的先行词可以是指物的名词或代词，也可以是指人的名词或代词。例如：
(1)She told her mother all that had happened.她把所发生的事情都告诉了她的母亲。(先行词是all，that在从句中作主语)
(2)I”ll buy you the bike(that)you saw in the shop yesterday.我要给你买昨天你在商店里看到的那辆自行车。(先行词是the bike， that在从句中作宾语)
(3)The village is no longer the village that it was before.这个村子不再是从前的那个村子了。(先行词是the village，that在从句中作表语)
(4)He that wants to eat the fruit must climb the tree.想吃果子的就得爬树。(先行词是指人的代词he，that在从句中作主语)
另有资料：
参考文献：
http://www.msvtcedu.cn/msvtc/Article/xx/jg/baox/wui/200603/6