in order to, so as to和to do “为了”引导目的状语, 后接动词原形, in order to/ to do在句中

的位置可前可后, 而so as to一般不放在句首；其否定式分别是: in order not to; so as not to;

not to do

In order to/To arrive on time, they started early.

他们为了按时到达很早就出发了。

Check your composition in order to/ so as to/ to avoid mistakes.

检查你的作文以避免错误。

We must do everything we can to help them.

我们要尽一切力量帮助他们。

so that和in order that 引导的是目的状语从句，从句中的谓语动词一般用“can(could) /may(might)/

 will(would) +动词原形”。in order that在句中的位置可前可后, 而so that一般不放在句首。

In order that they might arrive on time they started early.

他们为了按时到达很早就出发了。

He turned up the radio so that everyone could hear the news.

他把收音机的声音放大为了每个人都能听到这个消息。

He turned up the radio, so that everyone heard the news.

他把收音机的声音放大结果每个人都听到了这个消息。

要点归纳：

in order to 在句中的位置可前可后；so as to 一般不放在句首；to do在句中的位置可前可后；其否定式分别是: in order not to; so as not to; not to do

so that和in order that 引导的是目的状语从句，从句中的谓语动词一般用“can(could) /may(might)/ will(would) +动词原形”。