So that的用法
1．引导目的状语从句，“为了”：
= in order that,从句中一般要用情态动词。

He turned down his radio so that his neighbours wouldn’t hear it.
注：如主句和从句的主语相同，从句可改成so as to 或in order to 短语。

They got up early so that they could catch the early bus.= They got up early so as to/in order to catch the early bus.
2．引导结果状语从句，“以致”
1）这种从句一般不用情态动词，前面常用逗号与主句隔开。

He got up late, so that he missed the
train.
比较：
He raised his voice so that everyone
could hear him.
He raised his voice, so that everyone
heard him.
2) so…that…这一结构so后接形容词或
副词。

He is so young that he can’t go to school.
注：主从句主语相同，直接可转换成too…to…结构。

He is too young to go to school.
主从句主语不同，不定式前加for sb 引出动作的执行者。

He runs so fast that we all can’t catch up with him.
He runs too fast for us to catch up with him.
3) such…that…中，such后接名词。

It’s such an interesting book that we all like it. = It’s so interesting a book that we all like it.。