Unit 5 动词不定式-八年级英语上册同步精讲精练（人教版）
展开动词不定式
一、概念引入
1. 动词不定式名言：
（1）动词不定式作表语
To lose is to learn. 失败就是学习。
（2）动词不定式作主语
It is better to give than to take. 给予比接受更好。
（3）不定式作宾语
Expect to be treated as you have treated others.
你怎样待别人，就指望别人怎样待你。
（4）不定式作宾补
Adversity causes some men to break，others to break records.
逆境使一些人崩溃，也使一些人破记录。
（5）不定式作定语
There is a time to talk and a time to act.
该说的时候说，该做的时候做。
（6）不定式作目的状语
To find the exact answer，one must first ask the exact question.
要找到确切的答案，首先必须提出确切的问题。
2. 动词不定式定义：
动词不定式是一种非谓语形式（不能作谓语），基本形式是to do形式(to是不定式符号的标志，无意义，可以不翻译)
肯定式：to + 动词原形
否定式：not to + 动词原形
二、用法讲解
1.动词不定式的特征
动词不定动式是一种非谓语动词形式，它没有人称和数的变化，在句子中不能作谓语，但可以作除谓语之外的其它任何句子成分（主语、表语、宾语、宾语补足语、定语和状语）；动词不定式具有名词、形容词和副词的特征，同时还保持动词的某些特点，既可以有自己的宾语和状语，动词不定式和它的宾语和状语构成不定式短语。
2. 动词不定式在句子中的作用
动词不定式是由to+动词原形构成，在句中起名词，形容词和副词的作用，可以担任除谓语以外的其它任何成分。
（1）动词不定式作主语。例如：
To master a language is not an easy thing.
掌握一门语言不是一件容易的事情。
To teach English is my favorite. 教英语是我的爱好。
It's my pleasure to help you. 很乐意帮助你。
（2）动词不定式作宾语。
某些及物动词可以用动词不定式作宾语，这些动词有decide, begin, help, want, wish, like, forget, learn, ask等。例如：
I like to help others if I can. 如果有可能的话，我喜欢帮助别人。
I want to buy a new car when I have enough money.
我有钱时想买一辆新车。
（3）动词不定式作宾语补足语。例如：
We expect you to be with us. 我们希望你和我们在一起。
Please ask him to come here quickly. 请叫他快过来。
（4）动词不定式作表语。例如：
What I should do is to finish the task soon.
我应该做的是赶快完成任务。
The most urgent thing is to find the boy immediately.
当务之急是马上去找孩子。
（5）动词不定式作定语。例如：
There are many ways to solve the problem.
有许多方法能解决这个问题。
I have something important to tell you.
我有重要的事情要告诉你。
（6）不定式作状语。例如：
We went to the hospital to see our teacher.
我们去医院看了我们的老师。
She is making a test to get a kind of useful medicine from a Tibet flower.
她在做试验，从一种西藏花中提取某种有用的药物
3.不定式后接特殊疑问词的用法
不定式可以和疑问代词who, what, which及疑问副词when, how, where等连用，构成不定式短语，在句子中作主语、宾语、表语等。例如：
I don't know what to say. 我不知道说什么。
Can you tell me how to make a paper boat？ 你能告诉我怎样做一只纸船吗？
I don't know which topic to choose. 我不知道选哪个题目。
Where to stay for the night is a problem. 晚上在哪儿过夜还是个问题。
4.不定式的重要句型
（1）It’s＋adj.＋for (of)sb. to do sth.
当不定式作主语时，通常用it作为形式主语，而把真正的主语不定式结构后置。例如：
To meet you is a great pleasure. =It is a great pleasure to meet you.
非常高兴见到你。
To plant trees every year is necessary.= It is necessary to plant trees every year.
每年植树是必要的。
这种结构往往还要有一个逻辑主语。一般使用下面的结构：
1)It is +adj. ＋of sb.+to do sth.
It is selfish of you to eat the whole birthday cake.
你真是太自私了，吃光了整个蛋糕。
2)It is +adj. + for sb. + to do sth.
It is difficult for me to learn English well.
对我来说学好英语太难了。
【注意】
for和of引导的不定式结构的区别
表语形容词的语义不同是区别 for 结构和 of 结构的最重要标志。
1） 在“It is（was）＋adj.＋for sb.＋to do sth.”的句式中，作表语的形容词大多是表事物性质的静态形容词，如：essential，easy，difficult, important，necessary，possible，hard等等，这类形容词与for后面的名词（代词）关系不密切，无意义上的主表关系。例如：
It is necessary for us to practise speaking English every day．
每天练习说英语对我们来说是很有必要的。
2）在 “It is（was）＋adj．＋of sb.…”的句式中，作表语的形容词大多是表示人物特征的形容词。如：brave，careless，careful，clever，cruel，foolish，good，honest，（un）kind noble，polite，right，rude，sweet，silly，stupid，wrong等等。这些表示人物特征的形容词与of后的名词关系十分密切，有意义上的主表关系。例如：
It is kind of you（=You are kind）to send me a nice present．
谢谢你送我这么好的礼物。
It was stupid of her（=She was stupid）to make such a mistake．
出这样的错她真是太蠢了。
（2）主语＋动词＋too＋形容词／副词＋（for＋sb.）＋to+动词原形
表示“……太……而不能……”。例如：
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。
（3）主语＋动词＋……形容词／副词＋enough＋（for sb.）＋to+动词原形
表示“……对某人足以……”。例如：
We need several men strong enough to do the work.
我们需要几个强壮得足以做这件工作的人。
They bought a house large enough for ten persons to live in.
我们买了一栋房子，大得足以供十个人住。
He is competent enough to fill that position.
他足以胜任那职位。
（4）主语＋动词＋enough＋名词＋to＋动词原形
表示“……对某人足以……”。例如：
He has enough money (=money enough) to buy a car.
他有足够的钱买一辆汽车。
He hasn’t enough sense to realize his mistakes.
他没有足够的辨别力去认识自己的错误。
三、 巩固练习
I．单项选择。
1. ________ late in the morning, Bob turned off the alarm.
A. To sleep B. Sleeping C. Sleep D. Having slept
2. I'm going to the supermarket this afternoon. Do you have anything ________?
A. to be buying B. to buy C. for buying D. bought
3. I’ve worked with children before, so I know what ________ in my new job.
A. expected B. to expect C. to be expecting D. expects
4. She watched the children ________ in the garden.
A. to be played B. to play C. play D. to have played
5. The teacher asked us ________ so much noise.
A. don't make B. not make C. not making D. not to make
6.－I usually go there by train.
－Why not _______ by boat for a change?
A. to try going B. trying to go C. to try and go D. try going
7. Paul doesn't have to be made _______. He always works hard.
A. learn B. to learn C. learned D. learning
8. Tell him _______ the window.
A. to shut not B. not to shut C. to not shut D. not shut
9. She pretended _______ me when I passed by.
A. not to see B. not seeing C. to not see D. having not seen
10. Mrs. Smith warned her daughter _______ after drinking.
A. never to drive B. to never driver
C. never driving D. never drive
11 . The patient was warned _______ oily food after the operation.
A. to eat no B. eating not C. not to eat D. not eating
12. I saw him _______ out of the room.
A. go B. had gone C. has gone D. goes
13. —The light in the office is still on.
—Oh, I forgot _______.
A. turning it off B. turn it off
C. to turn it off D. having turned it off
14. He always prefers _______ a bicycle. rather than _______ on a crowded bus.
A. to ride；ride B. riding；ride
C. ride；to ride D. to ride；riding
15. The price is too low for customers________.
A. to believe B. believing C. believed D. believe
[真题链接]
1. The joke was so funny that it made him ____ again and again.
A. laugh B. to laugh C. laughed D. laughs
2. We stopped _________, but there was not any sound.
A. to listen B. listens C. listen D. Listening
3. Mr. Smith told his son _____ the football match because of the exam.
A. not to watch B. to not watch
C. not watching D. doesn’t watch
II．把下列的结果状语从句改为enough to或too…to的句式。
1. The room is so large that it can hold one hundred people.
_________________________________________________
2. The room is so small that it can’t hold one hundred people.
_________________________________________________
3. The text is so easy that a child can understand it.
__________________________________________________
4. The text is so difficult that a child can’t understand it.
__________________________________________________
5. He is so short that he can't be a good basketball player.
___________________________________________________
III.根据汉语提示，使用动词不定式补全下列句子（每空一词）。
1. 他还太小，无法做这事。
He is _______young a boy _______do it.
2. 他手头的工作太多了，不能跟我们去野餐。
He has ______ much work on hand ______ ______ picnicking with us.
3. 他跑得飞快，足以抓住那小偷。
He ran fast _______ ________ catch the thief.
4. 我们老师年纪已够得上退休了。
Our teacher is ______ ______ ______retire.
5. 按时完成作业对我们而言很重要。
It is important _______ _______ _______ finish the homework on time.
【答案与解析】
I．单项选择。
1. A。Bob 关了闹钟的目的是为了多睡一会儿，不定式结构在此作目的状语。
2. B。此处考查不定式作定语。表示“要……”，有将来的意味。
3. B。此题考查“疑问词+不定式”结构在句子中作宾语的情形。句子主语“I”与不定式短语之间是主动关系，因此要选to expect。
4. C。在表示感觉、视、听等生理活动的动词后，用作宾语补足语的不定式要省略to。
5. D。与其它非谓语动词一样，不定式的否定形式即在to do的前边加上否定词not。
6. D。why not 后面接不带to 的不定式，因此选D。
7. B。在主动句中，make后接不带to 的动词不定式，当其用于被动句时，to 不可省略。
8. B。tell sb. to do sth.的否定形式为tell sb. not to do sth.。
9. A。pretend 后应接不定式。其否定形式为pretend not to do sth.。
10. A。warn sb. to do sth. 的否定形式为warn sb. not to do sth. 此处用的是否定词never。
11. C。warn一词要求后用不定式，此句为被动句，否定形式为be warned not to do sth.。
12.A。see sb. do sth.看见某人做某事。这里是省略to的不定式作了宾语补足语。
13. C。forget to do sth.忘记（要）做某事。 这里是动词不定式作了宾语。
14. A。prefer to do sth. rather than do sth. 意为“宁愿做……不愿做……”。
15. A。too...to ...意为“太而不能”。句意为“价格太低让顾客难以相信”。
[真题链接]
1.A。句意：这个笑话如此好笑以至于让他笑了一次又一次。make + sb. + do(省略to的不定式) 表示“使某人做某事，让某人做某事”。
2. A。句意：我们停下来去听，但是那里没有任何的声音。stop to do sth. 表示 “停下来正在做的事情，去做别的事情”；stop doing 表示 “停止做某事”。根据句意，选A。
3. A。句意：史密斯先生告诉他的儿子不要看足球比赛了，因为要考试了。tell sb. to do sth.告诉某人做某事。tell sb. not to do sth. 告诉某人不要做某事。
II．把下列的结果状语从句改为enough to或too…to的句式。
1. The room is large enough to hold one hundred people.
2. The room is too small (not large enough) to hold one hundred people.
3. The text is easy enough for a child to understand.
4. The text is too difficult (not easy enough) for a child to understand.
5. He is too short (not tall enough )to be a good basketball player.
III.根据汉语提示，使用动词不定式补全下列句子（每空一词）。
1.too, to 2. too, to go 3. enough to 4. old enough to 5. for us to
