你记住，原则上主语是名词性结构的位置，所以名词是作主语的最常见形式，其次代词可以指代或替代名词作主语，数词也可以通过省略其后的名词而直接作主语。形容词名词化后也可以作主语。不定式和动名词都兼具名词性，所以可以作主语。名词性从句（陈述分句、疑问分句、感叹分句）可以作主语。个别情况下，介词短音和副词偶尔作主语。最后的个别情况可以忽略。原则上，介词短语、形容词、副词、现在分词、过去分词都不可以作主语。

1. 名词用作主语：

The pill is coated with sugar. 这药丸包了糖衣。

Black coffee leaves a bitter taste in the mouth. 不加奶的咖啡在嘴里留下了一些苦味。

2. 代词用作主语：

He is an able lawyer. 他是位很能干的律师。

I don’t discuss private matters with my colleagues. 我不和同事谈私事。

3. 数词用作主语：

Five is enough. 五个就够了。

Four from ten leaves six. 10减去4余6。

4. 名词化的形容词用作主语：

The poor always live beyond their income. 穷人的生活往往入不敷出。

Both young and old enjoyed themselves at the party. 年轻人和老人在聚会上都很开心。

5. 不定式用作主语：

To accept their offer would be foolish. 接受他们的帮助是愚蠢的。

To affect a policy is to have an effect on it. 影响一项政策就是对该政策具有一种影响。

6. 动名词用作主语：

Living in a town can’t compare with living in the country. 住在城镇比不上住在农村。

Watching the basketball match between the two teams was really exciting. 观看这两个球队的篮球赛实在是激动人心。

7. 名词化的过去分词用作主语：

The disabled are to receive more money. 残疾人将得到更多的救济金。

The accused was taken away in a police van. 被告已用警车带走。

8. 介词短语用作主语：

To Beijing is not very far. 到北京不很远。

From Yanan to Nanniwan was a three-hour ride on horseback. 从延安到南泥湾骑马要走三个小时。

9. 从句用作主语：

What you read influences your thinking. 你读的东西对你的思想有影响。

That he hasn’t phoned is odd. 令人感到奇怪的是他没打电话。

10. 句子用作主语：

“How do you do?”is a greeting. “你好!”是一句问候语。