现在分词可作的成分有：
1.表语：This book is interesting.
2.定语：Look at the girl standing there.
3.宾语补足语：I heard him singing in his room.
4.主语补足语：He was found playing basketball.
5.状语：Hearing his voice,we felt excited.
至于doing作主语、宾语的情况,那时的doing成为动名词,而不是现在分词.