人教版八年级上册Unit 5Do you want to watch a game show?动词不定式讲义

动词不定式
一、结构：动词不定式分为带to不定式（to do sth.）与不带to 不定式（do sth.）。其中，to不是介词，而是动词不定式符号，无意义，可以不翻译。
肯定式：to do 否定式：not to do
二、作用：在句子中可以作主语、宾语、表语、宾语补足语、定语或状语等。
三、用法：
1 作主语
不定式作主语时，谓语用单数(如并列时则用复数)。往往用it作形式主语，把不定式放在谓语后面。
常用结构为：It is + adj. /n.(+ for sb.) + to do sth.
It is + adj./n. + (of sb. )+ to do sth.
e.g. To watch movies is my hobby.
To fight with crime is dangerous.
It’s enjoyable for me to have dinner with you.
It’s necessary to learn every subject well.
It’s kind of you to check the information carefully.
2 作宾语
（1）动词+不定式：v.+ to do sth.
下列动词（短语）通常用不定式作宾语：help（带to不定式或不带to 不定式皆可）, need, want, hope, wish, expect, learn, decide, choose, would like, like, love, begin, start, stop, try, forget, remember等。
e.g. He decided to go on a vacation.
James chose to work in the city.
Teachers teach to learn something.
（2）动词（know, ask, show, teach, find out等）+疑问词+不定式: v. + wh- /how+ to do sth。
“特殊疑问句+不定式”相当于名词，常作宾语。
e.g. I don’t know what to do next.
(= I don’t know what I should do next.)
He told me how to do next.
(= He told me how I should do next.)
I can’t decide when to go there.
(= I can’t decide when I should go there.)
（3）不定式短语作宾语时，如果还带有宾语补足语，往往把不定式短语放在宾语补足语之后，用it 作形式宾语。
find/ think/ feel + it + adj. + to do sth. 其中，it为形式宾语，动词不定式为真正的宾语。
e.g. I find it necessary to learn a foreign language.
I think it difficult to answer this question.
I feel it relaxing to swim in the pool.
【注意】
（1）like, love, begin, start等动词后既可以接动词不定式，也可以接动词-ing形式，意义上差别不大。
e.g. I like singing, but I don’t like to sing now.
（2）stop, forget, remember, try等动词后面既可以接动词不定式，也可以接动词-ing形式，但意义上有差别。
stop to do sth. 停下（正在做的事）去做某事
stop doing sth. 停止做某事
e.g. I’m tired. Let’s stop to have a rest.
It’s time for class. Stop talking.
forget to do sth. 忘记要做某事（事情未做）
forget doing sth. 忘记做过某事（事情已做）
e.g. Don’t forget to turn off the light when you leave the room.
I forget telling you that before.
remember to do sth. 记得去做某事（事情未做）= don’t forget to do sth.
remember doing sth. 记得做过某事（事情已做）
e.g. We must remember to turn off the TV.
I remember giving you some books.
try to do sth. 尽力做某事
try doing sth. 尝试做某事
e.g. He tried to make his dream come true.
He decided to try living in the countryside for a while.
3 作宾语补足语
（1）动词+宾语+不定式: v. + sb. to do sth.
可以用动词不定式做宾补的动词及短语有：ask, tell, need, want, would like, help, wish, expect等。
e.g. He asked me to be careful.
I want you to speak to Tom.
（2）使役动词（make, let等）+ sb. / sth. + do sth.（作宾语补足语的要用不带to的动词不定式）
e.g. On weekends, my mother sometimes let me help with housework.
The teacher makes students sit quietly.
（3）感官动词+ sb. / sth. do sth. （过程）
感官动词+ sb. / sth. doing sth. （正在进行）
这类感官动词有：watch / see/find/look（视觉）, hear/listen（听觉）, feel（感觉）
e.g. I saw him talking with his friend when I walked into the room.
He saw Jack leave here.
4、作定语
不定式作定语，修饰名词或代词，通常位于这些被修饰的词后。
e.g. I have a lot of work to do.
What’s the best movie theater to go to
It’s the first to go there.
Hainan is the best place to go on a vacation in winter.
This is the best way to learn English.
5、作状语
常作目的状语，位于句首或句末。
e.g. He ran very fast to catch the first bus.
He came to the school to see his son.
To finish this work, he stayed up late.
原因状语，常位于形容词后表原因。
e.g. I am happy to see you.
I am sorry to be late again.
6、作表语
不定式可放在be动词后面，构成表语。
e.g. My question is when to leave.
His dream is to be a doctor.
Her work is to look after the babies.
四、不定式的重要句型
（1）主语＋谓语动词＋too＋adj. / adv.＋（for＋sb.）＋to do sth.
表示“（对某人来说）……太……以致于不能……”。
e.g. He walked too slowly to catch up with me. 他走得太慢而不能跟上我。
It is too dark in this room for me to read a book. 房间太暗，使我无法看书。
This problem is too difficult for them to settle. 这对他们来说真是一个难解的问题。
（2）主语＋谓语动词＋adj./ adv. ＋enough＋（for sb.）＋to do sth.
　　 表示“……对某人足以……”。
e.g. We need some men strong enough to do the work.
　　 They bought a house large enough for ten persons to live in.
（3）主语＋谓语动词＋enough＋n.＋to do sth.
　 表示“……对某人足以……”。
e.g. He has enough money (=money enough) to buy a car.