1.考察现在分词做原因状语.A
2.现在分词作状语,与主句的主语是主动和同步进行的关系.也就是说,主句的主语是后面的分词的动作的发出者,两个动作同时发生.
being a kind teacher ,he was loved by all his students.
having done,表示主动和完成,发生的动作要做主句的动作前完成.
having taken the pills.i went to bed.
3.to do .动词不定式,表示目的,结果,表示的动作在主句的动作以后.
he came here to fetch his books.