非謂語動詞主要包括不定式、動名詞和現在分詞。為了區分這三種不同的非謂語動詞的用法和含義，我們將分別從三種非謂語動詞在句子中做主語、賓語、賓語補足語、定語、狀語、表語以及一些特殊結構句型等角度來區分其用法和細微含義。

1.不定式和動名詞作主語的區別

(1)動名詞作主語通常表示抽象動作;而不定式作主語表示具體動作。

Smoking is prohibited(禁止)here.這里禁止抽煙。(抽象)

It is not very good for you to smoke so much.你抽這么多煙對你身體很不好。(具體)

(2)動名詞作主語時，通常用以表示一件已知的事或經驗。

不定式短語通常用來表示一件未完成的事或目的。

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

Driving a car during the rush hour is tiring.在高峰時刻開車令人厭煩。(經驗)

(3)不定式做主語，一般用it當形式主語，把作主語的不定式短語后置。

It took me only five minutes to finish the job.

2.不定式、動名詞和分詞作表語的區別

(1)不定式作表語

1)不定式作表語一般表示具體動作，特別是表示將來的動作。

To do two things at a time is to do neither.--次做兩件事等于未做。

What I would suggest is to start work at once.我的建議是立刻開始干。

2)如果主語是不定式(表示條件)，表語也是不定式(表示結果)。

To see is to believe.百聞不如一見。

To work means to earn a living.工作就是為了生活。

3)如果主語是以aim， duty， hope， idea， happiness， job， plan， problem， purpose， thing， wish等為中心的名詞，或以what引導的名詞性從句，不定式作表語是對主語起補充說明作用。

His wish is to buy a luxurious car in the near future.他的希望是在不遠的將來買一輛豪華轎車。

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)動名詞作表語：動名詞作表語，表示抽象的一般性的行為。

Our work is serving the people.我們的工作是為人民服務。

His hobby is collecting stamps.他的愛好是集郵。

(注)動名詞作表語時與進行時態中的現在分詞形式相同，但其所屬結構迥異，進行時態說明動作是由主語完成的。動名詞做表語，說明主語的性質或情況。

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.