先行词为不定代词、先行词是形容词级或被形容词级修饰、先行词是序数词或其被序数词修饰、先行词被the very， the only等词修饰、先行词包含了人和事物两方面的含义、先行词被same修饰，且指“同一物品”、关系代词在定语从句中作表语、主句是以who，which开头的特殊疑问句或先行词是who。
定语从句that的八种特殊用法引导定语从句的关系代词who，which有时可与that互换使用。但在下面情况，一般只用that.
一、当先行词为不定代词
anything， everything， nothing， any， little， one， few， much， all， none等时。如：
a.There isn't much that I can do. b.He is one of the few that can work it out in five minutes.
二、当先行词是形容词级或被形容词级修饰时。如：
a.The book is the best that I have read. b.This is the biggest laboratory that we have ever built in our university.
三、当先行词是序数词或其被序数词修饰时。如：
a.It is the third one that I've bought. b.This is the first place that I‘ve ever visited.
四、当先行词被the very， the only等词修饰时。如：
a.Is this the very museum that you visited the other day? b.This is the only book that I need at present.
五、当先行词包含了人和事物两方面的含义时。如：
They talked of things and persons that they remembered in the school.
六、当先行词被same修饰，且指“同一物品”时。如：
She is wearing the same dress that she wore yesterday.
七、关系代词在定语从句中作表语时。如：
a.This is no longer the place that it used to be. b.He is not the man that he was.
八、当主句是以who，which开头的特殊疑问句或先行词是who时。如：
a.Which is the book that he bought yesterday? b.Who that you have ever seen can beat him in the game?
that 引导的结果状语从句1)由that引导的状语从句。
What have I done that you should treat me like this? 我究竟干了什么，你竟这样对待我？
2)结果状语从句中的that 有时还可以省列。
He is such a marvelous joker you can't help laughing. 他的笑话讲得那么出色，你会禁不住哈哈大笑。
从结构的角度讲，区分that是引导状语从句还是引导定语从句可以根椐从句的成分是否完整来判断。定语从句通常是不完整的，即从句所修饰的先行词会在从句中充当某成分。如：It is a story that people believe. 这是一个人们都相信的故事。(这里story作believe的宾语。)
