so as to和as to 的区别

so as to 以便,为的是
例句：
He ran quickly so as to catch the last bus.
他跑得很快以便赶上那末班车.
Look for the old so as to learn the new.
温故而知新.
与 in order to区别：
两者都可以引导目的状语从句“为了…”,in order to在句子前面或中间皆可,而so as so不能放在句首,如：
In order to pass the exam,he studied even harder.
We started early in order to arrive before dark.
as to 关于,至于
如：as to that,i will contact you later.