一、
非谓语动词作状语的区别：
1.
不定式：目的和结果状语，
2.
分词：时间、原因、条件和伴随方式状语
二、不定式短语作状语可以放在句首，短语后需要用逗号；也可以放在句尾，但是前面不能加逗号。如：
前置：To enable the students to return to their classrooms, the retired man donated most of his savings to the school damaged by the earthquake in yushu.
后置：The retired man donated most of his savings to the school damaged by the earthquake in yushu to enable the students to return to their classrooms.
目的状语的意思是：为了能使那里的学生重返教室，那位退休老人把自己大多数积蓄捐赠给了
玉树被地震破坏了的学校。
三、后置的分词短语一般用作伴随方式状语，如果状语部分较长，前面用逗号与句子的主体部分分开，如：
The retired man donated most of his savings to the school damaged by the earthquake in yushu, enableing the students to return to their classrooms.
意思是：那位退休老人把自己大多数积蓄捐赠给玉树被地震破坏了的学校，（以此方式）使得那里的学生能够重返教室。