赖世雄教你学英语语法
非谓语动词
3-1：动名词做主语
例：working with him is fun.
（和他一起工作很有趣。）
seeing is believing.
（眼见为信。）
losing his fortune drove him mad.
（失去他的财富使他发疯了。）
not knowing how to do it was a shame to him.
（不知道怎么做此事，对他是件惭愧的事。）
注意
上述各例中，working, seeing, losing以及not knowing均做主语，故为动名词。
注意
动名词做主语时，仍有动词的意味，若该动名词原为及物动词，之后仍须加宾语。宾语即使为复数，所形成的动名词短语应视为单数，之后接单数动词。
例：climbing mountains help (to) relax one's tension.(x)
----climbing mountains helps (to) relax one's tension.(o)
（爬山可帮助人消除紧张。）
理由：本句并非mountains做主语，而是整个爬山的动作做主语，所以原词后动词用单数。
注意
动名词短语做主语时，也可以被虚主语it代替，而将该动名词短语移至句尾，改变成不定式短语。
故上例可改写为：
例：it helps (to) relax one's tension to climb mountains.
it drove him mad to lose his fortune.
it was a shame to him not to know how to do it.
注意
惟在it is no use的结构中，真主语仍应为动名词。
例：it is no use crying over spilt milk.(o)
（覆水难收。）
it is no use to cry over spilt milk.(x)
这是习惯用法，同学宜牢记。
例：it is no use reasoning with such a stubborn man.
= it is (of no use/useless) to reason with such a stubborn man.
= there is (no use/no sense/no point) in reasoning with such a stubborn man.
（和这样固执的人讲理是没有用的。）