非谓语动词之不定式.docx

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 well.
◆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.
To speak English well, one must have a lot of practice.
②作原因状语
I’m glad to see you again.
I am sorry to hear your grandma is ill.
③作结果状语
He is to young to go to school.
He is old enough to go to school.
7.作插入语
作插入语，为独立成分，位置活泼。但需与其它成分用逗号隔开。
to be honest, to tell the truth, to begin with, to make matters worse, to be frank(坦率地说)等。
8. It's adj. for sb.to do sth. 和 It's adj.of sb.to do sth.
1）It's adj. for sb.to do sth.做某事对某人来说如何如何。
其中的形容词一般为描述事物的特征、特点，表示客观形式的形容词，如easy, hard, difficult, interesting, impossible等：例如：
It’s very hard for him to study two languages. 对他来说学两门外语是很难的。
= To study two languages is very hard for him
2） It's adj.of sb.to do sth.某人做什么真的是怎样怎样。
其中的形容词一般描述人的性格，品质，性情，表示主观感情或态度的形容词，如good, kind, nice, clever, foolish, right。例如：
It’s very nice of you to help me. 你来帮助我，你真是太好了.
=You are very nice to help me
9.用作介词的to，后接doing.
be used to习惯于;
look forward to期望;
pay attention to注意;
prefer…to…比起…更喜欢…
◆记住如下惯用法：
①Why not do
②had better (not) do
You'd better give back the books to the library on time.
③would rather (not) do than do sth.
④不定式在介词but, except后面时，若but等前面有实义动词do的任何形式时，则后接不带to的不定式；否则带to.
They did nothing but wait.
He wants to do nothing but go out. 他只想出去玩。
What do you like to do besides swim?除了游泳你还喜欢做什么？
They had nothing to do but wait.
=They had no choice but to wait.
He wants to believe anything but to take the medicine. 除了吃这药，他什么都信。
⑤prefer to sth. rather than do sth.
⑥used to do sth.
⑦will/would you please (not) do sth.
⑧do sth. to do sth.采取措施做…
⑨want to do sth.想做…/want doing想被…
⑩have something to do with…与…有关

5