动词不定式的用法
一、动词不定式表示目的,作目的状语。
1. I stayed there to see what would happen. to后面所接的see是前面这个动作stayed there的目的。意为“我呆在那儿，(目的是)看看会发生什么。”

2.有时为了强调,可用in order to或so as to。
eg: Bob took down my telephone number so as(in order)not to forget it.

3.由in order to引导的目的状语，既可以置于句尾，也可以置于句首,而由so as to引导的目的状语,只能置于句尾,而不能置于句首。比较:
They started early in order to get there in time.(正)In order to get there in time, they started early. (正)They started early so as to get there in time. (正)So as to get there in time, they started early.(误)