in order to 与so as to 都有'为了'之意，放在句中时，可通用；但so as to 只能放在句中。
in order to“为了”，只能表示目的，其位置在句首或句中均可，否定结构用in order not to ,in order to比so as to更正式。
固定用法：in order to do something，to后面跟动词原形。
例句：
I went home in order to change my clothes. 我回家为了换衣服。
She arrived early in order to get a good seat.她为了占个好座位，早早就到场了。
In order to get a complete picture, further information is needed.要想了解事情的全面情况，还需要更多信息。
He brought up the issue in order to embarrass his opponent during the debate.在辩论期间，他提出了这个问题就是为了让反方无言以对。
I gave John three dollars in order to buy lunch.我给了约翰三美元去买午餐。
so as to'为了'，表示目的，其位置一般在句中，否定结构用so as not to .
固定用法:so as to do something, to 后面跟动词原形。
We took off our shoes so as to avoid scratching the newly finished floors.我们都脱掉了鞋子，以免划伤新地板。
We went early so as to get good seats.我们早去就是为了占个好位置。
Mail your package early so as to ensure its timely arrival. 你要是早点把包裹寄出去，就可以保证快递及时送达。
