1.1.3动名词或不定式作主语
a.动名词作主语
See him makes me angry.（错误）
Seeing him makes me angry.（Seeing为动名词）
看到他就令我生气。
b.不定式作主语
See him is my purpose of coming here.（错误）

To see him is my purpose of coming here.（To See为不定式）

注意：
1）不定式或动名词短语作主语时，往往会形成主语太长的现象，通常均可用代词it作形式主语，置于句首，而将真正的主语（不定式或动名词短语）移至句尾。动名词移至句尾时，通常改为不定式短语。
Collecting stamps is one of his hobbies.
=It is one of his hobbies to collect stamps.
2）有时我们亦可见到it代替的动名词移至句尾时，仍保留动名词形成不定式短语。但此种用法并不普遍，初学语法者应尽量避免。
It is interesting to learn English.（佳）
It is interesting learning English.（可）
3）例外：
It is no use + 动名词短语
It is no use asking him for help.
=It is useless + 不定式短语
=It is of no use + 不定式短语
=There is no use in + 动名词短语
There is no sense in + 动名词短语
There is no point in + 动名词短语