非谓语动词之不定式

动词不定式

一．定义

1.由“to+动词原形”构成, 是动词的一种非谓语形式, 在句中作除谓语之外的其他成分。to是不定式的标志，无词义。不定式无人称和数的变化，

2.肯定形式to do; 否定形式not to do。

3.不定式仍有动词的特点，即可以有自己的宾语和状语。

二．功能：不定式有名词、形容词、副词的功能，在句中作主语、宾语、表语、定语、宾语补足语和状语。就是不作谓语。

1.作主语(谓语动词使用三单形式) , 一般表示具体的某次动作。

①直接放在句首

To help each other is good.

②用it作形式主语，而将作真正的主语（不定式）置于句末，如以下结构：

◆It is easy/ hard/ difficult/important/necessary/interesting…(for sb.) to do sth.

It is important for us to learn English wel l.

◆It is our duty to do sth.

It is our duty to keep our classroom clean.

注：-ing形式与不定式作主语之区别：

-ing作主语，通常是某种经常性的活动，即泛指某种抽象的动作；不定式作主语，通常表示某次具体的动作。

2.作宾语

①常只跟to do作宾语的动词如下：hope, plan, decide, expect, agree, choose, seem, happen, learn, teach, prepare, promise, wish, wait, fail, afford, manage, refuse, pretend, offer, arrange 等

②即跟to do又跟-ing作宾语，意义差别不大的有：begin/start; continue;

③即跟to do又跟-ing作宾语，且意义差别很大的有：remember, forget, mean, try, regret, stop, can’t help等。略。

④“疑问词/whether to do”作宾语。“疑问词+不定式”作宾语= 该疑问词引导

的一个宾语从句。

I don’t know how to finish the work.=I don’t know how I can finish the work.

⑤用it作形式宾语，将真正的宾语不定式放在最后。

I find it difficult to learn English well.

I don’t think it right to do it that way.

3.作表语

①放在be/ seem/ appear等之后，表示主语的内容是将来的某次(具体)的动作。

His dream is to be a doctor.

4.作定语

①放在其修饰的词之后，表将来。与被修饰的词有被动关系，不定式必是及物动词。

I have a lot of homework to do.

I have no pen to write with.

Give me a piece of paper to write on. 给我一张纸写字。

②当被修饰的名词是序数词(包括last, only, next)和最高级，或有序数词(包括last)和最高级来修饰时，要用不定式作定语。

Lucy is always the first to come and the last to leave.

The last one to arrive pays the bill.

I don’t think him to be the best man to do the job.

③当名词为复合不定代词something, anything…等时，常用不定式作定语。

Do you have something to say for yourself?

There was nothing to bring home that morning. 那天早上（他回家时）两手空空。

④不定式常作下列的名词定语：time, way, place, plan, chance, decision, promise, effort,等。

He needs time to do his homework.

Our teacher had no time to think about rest.

Is there a good place to hang out?

The old man is looking for a quiet place to live.

I know the best way to go around the city.

5.作宾语补足语

①以下动词，后接宾语，再接to do作宾补语。tell, want, ask, teach, expect, invite, order, help, like, send, advise, choose, beg, allow, encourage, force, wish, warn, hate 等。构成ask/tell sb. (not) to do sth.

②以下动词，后接宾语，再接省to的不定式作宾补语。若变为被动语态，添上to。

一感：feel

二听：listen to, hear

三让/使：let make, have

五看：look at, see, watch, notice, observe

半帮助：help

The teacher made him say the word like this.

老师让他像这样说这个单词。

Could you help me (to) carry the heavy box？

你能帮我搬这个重箱子吗？

The teacher made the two students stand for three hours.

→The two students were made to stand for three hours.

6.作状语

①作目的状语to do, in order to do,等，

I come here only to say good-bye to you.我来仅仅是向你告别。

In order not to forget, I have written it down.

为了强调，把不定式放在句首

To save the energy, turn off the hot water after you take s shower.