doing可以做除谓语动词之外的所有成分。例：
① Interacting with others entertains the old man. 和别人交流让这个老人很开心。
interacting with others做主语。
② The old man enjoys interacting with others. 这个老人喜欢和别人交流。
interacting with others做宾语。
③ The old man’s hobby is interacting with others. 这个老人的爱好是和别人交流。
interacting with others作表语。[/p]
