请问现在分词短语作伴随状语与现在分词短语作宾语补足语、还有动名词怎么区分?

分词短语作伴随状语,主要是描述句子主语的,而宾语补足语主要是补充说明宾语的情况,例如：
Hearing that his son failed again in maths,she kept him doing maths exercises for an hour every day。
这里Hearing that his son failed again in maths是伴随状语,是指 she heard that his son。。。；而doing maths exercises for an hour every day 指补充说明宾语him的,言下之意,He did maths exercises for an hour every day。
动名词是名词性质的,所以在本来需要名词的地方用动词,就得用动名词,例如介词一般后加名词,所以介词后加动词一定要用动名词,另外,一些动词（finish,enjoy,practise,avoid,。。)可以直接加动名词做宾语,动名词还可以作主语（因为主语一般是名词之类的东西充当）,如：Waiting here is not helpful。