定語從句用法：關係代詞that 的用法
1）不用that的情況
a) 在引導非限定性定語從句時。
(錯) The tree, that is four hundred years old, is very famous here.
b) 介詞後不能用。
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作爲定語從句的關係代詞的情況
a) 在there be 句型中，只用that，不用which。
b) 在不定代詞，如：anything, nothing, the one, all, much, few, any, little等作先行詞時，只用that，不用which。
c) 先行詞有the only, the very修飾時，只用that。
d) 先行詞爲序數詞、數詞、形容詞最高級時，只用that。.
e) 先行詞既有人，又有物時。
舉例：
All that is needed is a supply of oil.
所需的只是供油問題。
Finally, the thief handed everything that he had stolen to the police.
那賊最終把偷的全部東西交給了警察。
定語從句的.種類和用法
用來說明主句中某一名詞或代詞（有時也可說明整個主句或主句中一部分）而起定語作用的句子叫作定語從句。
一、關係代詞引導的定語從句
1. 關係代詞用來指代先行詞是人或物的名詞或代詞
句子成分 用於限制從句或非限制性從句 只用於限制性從句
代替人 代替物 代替人或物
主語 Who which that
主語 Whom which that
賓語 Whose（=of whom） whose（=of which）
例1：This is the detective who came from London.
例2：The book which I am reading is written by Tomas Hardy.
例3：The desk whose leg is broken is very old.
例4：This is the room that Shakespeare was born in.
2.關係代詞的用法
（1）如果先行詞是all，much，anything，something，nothing，everything，little，none等不定代詞，關係代詞一般只用that，不用which.例如：
All the people that are present burst into tears.
