非谓语动词主要包括不定式、动名词和现在分词。为了区分这三种不同的非谓语动词的用法和含义，我们将分别从三种非谓语动词在句子中做主语、宾语、宾语补足语、定语、状语、表语以及一些特殊结构句型等角度来区分其用法和细微含义。

1.不定式和动名词作主语的区别

(1)动名词作主语通常表示抽象动作;而不定式作主语表示具体动作。

Smoking is prohibited(禁止)here.这里禁止抽烟。(抽象)

It is not very good for you to smoke so much.你抽这么多烟对你身体很不好。(具体)

(2)动名词作主语时，通常用以表示一件已知的事或经验。

不定式短语通常用来表示一件未完成的事或目的。

Climbing mountains is interesting.爬山很有趣。(经验)

Driving a car during the rush hour is tiring.在高峰时刻开车令人厌烦。(经验)

(3)不定式做主语，一般用it当形式主语，把作主语的不定式短语后置。

It took me only five minutes to finish the job.

2.不定式、动名词和分词作表语的区别

(1)不定式作表语

1)不定式作表语一般表示具体动作，特别是表示将来的动作。

To do two things at a time is to do neither.--次做两件事等于未做。

What I would suggest is to start work at once.我的建议是立刻开始干。

2)如果主语是不定式(表示条件)，表语也是不定式(表示结果)。

To see is to believe.百闻不如一见。

To work means to earn a living.工作就是为了生活。

3)如果主语是以aim， duty， hope， idea， happiness， job， plan， problem， purpose， thing， wish等为中心的名词，或以what引导的名词性从句，不定式作表语是对主语起补充说明作用。

His wish is to buy a luxurious car in the near future.他的希望是在不远的将来买一辆豪华轿车。

The function of Louis Sullivan’s architecture was to provide large uninterrupted floor areas and to allow ample light into the interior.

The most important thing is to negotiate with them about the future of the plant.

(2)动名词作表语：动名词作表语，表示抽象的一般性的行为。

Our work is serving the people.我们的工作是为人民服务。

His hobby is collecting stamps.他的爱好是集邮。

(注)动名词作表语时与进行时态中的现在分词形式相同，但其所属结构迥异，进行时态说明动作是由主语完成的。动名词做表语，说明主语的性质或情况。

People cannot but feel puzzled， for they simply cannot understand how he could have made such a stupid mistake.

His victory in the final was no more convincing than I had expected.