如:
In handing down this sentence， Judge said it‘s nessesary to deter others
这里的In doing 相当于When handing down this sentence
表示“在做...时”，可看做一个时间状语
doing开头一般来说 是动名词做主语，位于句首，谓语动词要用单数。
Playing on the beach is a pleasant thing for me.
Doing exercise every day makes us healthier and healthier.
in doing 开头的句型
1，be fortunate in doing sth做某事是幸运的 .
2，be busy in doing sth忙于做某事 .
