1.作主语：通常被看作是单数
不可数名词,所以
谓语动词用第三人称单数形式.
Driving fast is very dangerous.
Swimming is my favourite sport.
Painting is an art.
Hearing the bad news made him cry.
注意：
现在分词作主语时,和
动词不定式一样,当它是较长的短语时,常常用it作形式主语,而把现在分词放到句末.
如：It's nice spending the holiday at the beach.
It's tiring working late.
现在分词作主语时的常用句型：
a waste of time
no good/no use
It +be+ little/hardly any use + V-ing分词
not/hardly worth
worth/worthwhile
如：It's no use complaining.
It's no good smoking a lot.
It's a waste of time doing such a thing.
no
no sense in（没有道理）
There +be+ no point in（毫无意义） +V-ing分词
no use in
Nothing worse than(没有比...更糟糕的)
如：There was no knowing what he was doing.
There is no point (in) doing so.这么做,毫无意义.
经常跟在it +be后面的形容词,然后接
动名词作实际主语的形容词还有：
Odd古怪的\x09Crazy疯狂的\x09Hopeless无望的\x09Nice
Funny好笑的\x09Foolish愚蠢的\x09interesting\x09Tiring累人的
better\x09terrible\x09Enjoyable愉快的\x09Pointless无意义的
2作
表语：-ing分词作表语多和
系动词be连用.注意：如果主语用了不定式,表语也要用不定式；同样地,如果主语用的是-ing分词,表语也应用-ing分词.即,作主语和表语的动词在形式上的一致.
如：Seeing is believing=To see is to believe.
My favourite sport is swimming.
Her only hobby(爱好) is collecting stamps.
☆注意：现在分词作表语和动词不定式作表语的区别在于：现在分词表示习惯性动作；而不定式表示一次性的具体动作.
如：My plan is to finish my homework before tomorrow.
My favourite sport is swimming.
3. 作宾语
英语中,有相当一部分动词后,只能接-ing分词作宾语.
这类动词主要有：
Admit承认\x09advise\x09Anticipate期望做..\x09Detest憎恨做...
Defer推迟\x09suggest\x09Escape逃避做..\x09Quit停止做..
Deny否认\x09Miss错过\x09Avoid避免做...\x09Tolerate忍受..