help others is neccessry.还是helping others?

题目

help others is neccessry.还是helping others?
help others 做主语是名词结构么?
可是已经有others了啊？

答案

help others is neccessry.是不对的
动词不能做主语.
To help others is necessary.
不定式可以做主语
Helping others is necessary.
动名词作主语