一般所见到的句子结构中，通常是以名词作主语，但除了名词以外还可以用代词、动名词、不定式短语、名词性从句、名词短语、表距离的地点副词短语等做主语。分别说明如下：
1、名词作主语。
The child is my daughter.
2、代词做主语。
He always keeps his promise.
3、动名词或不定式短语作主语。
动词一定一定不能做主语，要变成动名词或者不定式短语，如此才能和名词对等。
Seeing her makes me angry.
To see him is my purpose of coming here.
（1）那么什么情况下用动名词做主语呢？一般情况下是用来表示已知的事实或曾经做过的经历。
例1.collecting stamps is one of my hobbies.
例2．Listening to music makes me happy.
这里collecting stamps和Listening to music都是以往的一种经历。
（2）用不定式做主语时，通常表示一种意愿、目的或尚未做的事。
To study in the United States is my greatest desire.
To go to Japan for a visit is my plan for this year.
注意：
不定式或动名词作主语时往往造成主语太长的情况（如上），故通常用代词it置于句首做形式主语，而将真正的主语移至句尾。但是，动名词移至句尾时通常要改为不定式短语。
Collecting stamps is one of his hobbies.
= It is of his hobbies to collect stamps.
To study in the United States is my greatest desire.
= It is my greatest desire To study in the United States.
例外：It is no use + 动名词短语。这里不可使用不定式短语，千万千万记住哦！
It is no use crying over split milk.
但是，当你把no use 换成useless或者ofone use 后面可跟不定式短语。
这期就到这里，欢迎大家讨论交流，我们下期再见