so as to do sth.意为"以便做某事"，在句中作目的状语，也可以用in order to do sth.来代替。例如：
(1) They started early so as to / in order to catch the first bus.
他们早早出发是为了赶第一班公共汽车。
(2) He read the new words again and again so as to / in order to learn them by heart.
他一遍又一遍地读单词，是为了能把它们背下来。
A. so as to do sth. / in order to do sth. 的否定形式是so as not to do sth. / in order not to do sth.，意为"为了不做某事"。例如：
(1) The children went in quietly so as not to / in order not to wake their father.
孩子们轻轻地走进去，为的是不弄醒父亲。
(2) We arrived at the station in time so as not to / in order not to miss the train.
为了不误火车我们及时赶到车站。
B. in order to do sth.不但可以用在句子中间，也可以用在句首，但so as to do sth.不能用在句首，只能用在句子中间。例如：
(1) In order to go to college, he works very hard.
为了上大学，他非常努力地学习。
(2) In order to keep our country clean, everybody must fight pollution.
为了保持我们国家清洁，每个人都必须与污染作斗争。
C. so as (not) to do sth.可以转化成so that句型；in order (not) to do sth.可以转化成in order that句型。例如：
(1) Everybody must help to fight pollution so as to keep our country clean.
Everybody must help to fight pollution so that we can keep our country
clean.
(2) They started early so as to catch the first bus.
They started early so that they could catch the first bus.
(3) The children went in quietly in order not to wake their father.
The children went in quietly in order that they would not wake their father.
