何时用不定式何时用分词和动名词

何时用不定式何时用分词和动名词

Ⅰ.动名词和不定式做主语的相同点

1.不定式短语和动名词做主语时，常常为了保持句子的平衡，用it来做形式主语，如：

It is not easy to learn English well.

It is no use asking him for help.

2.如果主语用了不定式,表语和宾语也要用不定式;主语用了动名词,表语和宾语也要用动名词,这在英语中称为对称性,如:

To see is to believe. = Seeing is believing. (眼见为实)

(85)It is better to stay home than _A__ out.

A. to go

B. going

C. go

D. gone

Ⅱ.动名词和不定式做主语的不同点

1.不定式做主语常表示具体的某一动作;表示泛指或一般的抽象的概念时,多用动名词,如:

(92)_B_ is a good form of exercise for both young and old.

A. The walk

B. Walking

C. To walk

D. Walk

2.在”There/It +be+ no use(good/help/need)”之后常用动名词做主语,而少用不定式,如:

It /There is no use crying over the split milk.

It /There is no help taking this medicine.

★但是如果该句型中用了for引出不定式的逻辑主语,就只能用不定式,如:

(93) There is no good for us to do that exercise.

3.不定式可以和when, where, how, what, whether等连用,在句子中做主语,宾语和表语,而动名词则不能,如: How to solve the problem is a hot potato.

Where to put the box seems hard to decide.

Whether to do it hasn’t been decided.

What to do next is up to you.

时态、语态及其基本用法

A. 不定式

1．不定式的时态、语态有三种形式：①一般式，如，to write / to be written ;②进行式，如，to be writing / to have been writing;③完成式，如，to have written / to have been written 。

2．基本用法

①不定式的一般式，表示的动作与谓语动词表示的动作同时发生，有时也发生在谓语动词表示的动作之后。如：

He seems to know this.(=It seems that he knows this.)

I hope to see you again.(=I hope that I’ll see you again.)

He doesn’t like to be laughed at. (=He doesn’t like that he is being laughed at.)

②不定式的进行式，表示不定式的动作正在进行，与谓语动词表示的动作同时发生。如：

When the mother went into the room, the boy pretended to be sleeping. (=… , the boy pretended that he was sleeping .)

I heard the English song being sung by him. (=I heard that the English song was being sung by him.)

③．不定式的完成式，表示的动作发生在谓语动词表示的动作之前。如：

I am sorry to have kept you waiting so long. (= I am sorry that I kept you waiting so long. )

Having been well written, the book was translated into many languages. (=Because it had been well written, …)

B. 分词

1.只有现在分词才有时态和语态形式的变化。现在分词的时态、语态有两种形式：①一般式，如，doing / being done;

②完成式，如，having done / having been done 。

2.基本用法

①现在分词的一般式，表示的动作与谓语动词表示的动作同时发生，或在谓语动词表示的动作之前发生。如：

The boys and girls went to school, singing and dancing all along the way .

They all jumped with joy ,hearing the good news.

The girl could not help crying ,being criticized in the public.

②现在分词的完成式，表示的动作在谓语动词表示的动作之前已发生，常用作时间状语或原因状语。如：Having done the work very well ,he was praised by the teacher.

Having been shot by a bullet, the man fell down dead.

C．动名词

1.动名词的时态、语态有两种形式：①一般式，如，writing / being written ; ②完成式，如，having written / having been written 。

2.基本用法

①动名词的一般式不表示动作正在进行，但作具有状语性质的宾语时，动名词一般式表示的动作与谓语动词的动作同时发生。如：

The teacher is busy collecting the stude nts’ exam papers.

②动名词的完成式在作具有状语性质的宾语时，表示的动作在谓语动词的动作之前已发生。如：

He was praised by the teacher for having done the work wonderfully.

He felt so sorry for not having been given the chance to work in the company.

三、不定式、分词、动名词的词性特征和句法功能

1．不定式既有动词的一些特征，又具有名词、形容词、和副词的句法功能，因此，不定式在句中作：主语、表语、宾语、宾语补足语、定语、状语、独立成分。

2．分词即具有动词的一些特征，又具有形容词和副词的句法功能，因此，不定式在句中作：表语、宾语补足语、定语、状语、独立成分。

3．动名词，顾名思义，既有动词的一些特征，又具有名词的句法功能，因此，动名词在句中作：主语、表语、宾语、定语、同位语。

四、不定式、分词、动名词句法功能用法的比较

1. 从上面不定式、分词、动名词的词性特征和句法功能中，我们不难看出它们在句子中的作用既有较多的共性，又有稍微的差异：

a.相同的句法功能：①不定式、分词都能作：表语、定语、宾语补足语、状语、独立成分；②不定式、动名词都能作：主语、表语、宾语；③不定式、分词、动名词都能作：表语、定语。

b.不同的句法功能：不定式可作：同位语。如：

That was her desire, to go to America for further study after finishing middle school.

2.正确运用好不定式、分词、动名词

⑴．不定式、分词、动名词作表语时的比较。请看例句：

①My job is to teach the students English.

②My job is teaching the students English.

③My job is interesting.

④I am interested in English.

辨析：A. ①不定式与动名词作表语一般可以互换使用，在意义上没有多大差别，且其形式差异较大，很容易把握, 如上面例句的①②；②现在分词和动名词同形，在作表语时，学生不易识别。分辨方法有三：a）分词作表语说明主语的性质特征，回答how的问题；不定式和动名词作表语则说明主语的内容，回答what 或doing what 问题, 如：My job is interesting.(=How is my job?) ; My job is teaching ( to teach ) the students English. (=What is my job?); b）动名词具有名词的句法功能，也能做主语，我们不妨把句中的表语转换成主语，如果句子成立，则是动名词作表语，否则是现在分词作表语。如：My job is teaching the students