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(共20张PPT)
语法 -- 动词不定式
Infinitives
动词不定式
1.定义
动词不定式是非谓语动词的一种，它没有人称和数的变化，在句中不能作谓语。
2.构成
动词不定式的基本形式是“to+动词原形”，常写作to do(有时to可以省略)，否定形式为not to do 。
He wants to sit. Tell him not to live alone.
动词不定式具有名词、形容词和副词的特征，因此可在句中作主语、宾语、宾语补足语、定语和状语等。
3.用法
No.1 作主语
动词不定式作主语。动词不定式作主语时，一般位于句首。单个不定式短语作主语时，谓语动词用第三人称单数形式。
如果动词不定式太长,为避免头重脚轻，则可用it作形式主语,把真正的主语放在后面，构成 " It is +adj. for/ of sb. to do sth."句型。
To learn a foreign language is important for us.
= It's important for us to learn a foreign language.
No.1 作主语
It is +adj. for/ of sb. to do sth.
for: adj.多为描述不定式行为的特征（important/ necessary / interesting 等.）
of: adj. 多为 描述主语的品质特征（kind / nice / friendly / wise / foolish 等.）
It is easy for her to learn English well.
It is clever of you to solve the problem.
常接动词不定式作宾语的动词有：
想要 拒绝 忘记 (want, refuse, forget)
需要 努力 学习 (need, try, learn)
选择 同意 帮助 (choose, agree, help)
希望 决定 开始 (hope/wish/expect, decide, begin/start)
动词不定式作宾语
No.2 作宾语
1、动词+ to do sth.
主语+谓语+ to do sth
No.2 作宾语
主语+谓语+ to do sth
I often help my classmate (to) finish his math homework after school.
我经常在放学后帮同学完成数学作业。
She decides to finish her homework before watching TV.
她决定看完电视前先完成作业。
No.2 作宾语 主语+谓语+ 疑问词 + to do sth
2.动词＋wh- + to do
We always ask our math teacher how to solve difficult word problems.
我们总是问数学老师如何解决复杂的应用题。
I'm sorry I don't know when to start.
对不起我不知道什么时候开始。
No.2 作宾语 主语+谓语+ 疑问词 + to do sth
3.部分动词（like, love, begin, start 等）后既可接动词不定式，也可接动名词，意义差别不大。
4.结构 “ find / think / feel + it + adj.+ to do”中，it是形式宾语，动词不定式是真正宾语。
I think it important to finish our homework on time every day.
我认为每天按时完成作业很重要。）
动词不定式作宾语补足语说明宾语所做的动作，常用的动词有：
tell, ask, want, teach, promise, expect, wish, invite, would like 等。
My mother asks me to clean my room.我妈妈要求我打扫房间。
The teacher encourages us to speak English inclass.
老师鼓励我们在课堂上说英语。
No.3 作宾语补足语 主语+谓语+宾语 ( sb./sth. )+to do sth
动词 + 宾语（sb./sth.) + to do sth.
No.3 作宾语补足语
2. 动词+宾语+不带to的不定式
动词多为感官动词、使动词。
一感：feel
二听：hear, listen to
三使：make, let, have
四看：see, notice, watch, look at
No.4 作表语
1. 主语 + be + to do sth
主语多为 duty / wish / hope / idea / plan / ambition/ dream / work / job 等 名词
1. My ambition is to be a singer. 我的梦想是成为一名歌手。
2. His work is to clean the classroom every day.
他的工作是每天清扫教室
动词不定式作定语时，应放于被修饰的名词或代词之后。例：我想吃点东西。
I want to have something to eat.
她得到一份照顾一位老人的工作。
She got a job to take care of an old man.
No.5 作定语
No.6 作目的状语
动词不定式（to do，否定式 not to do ）作目的状语，用于说明动作的目的，即“做某事是为了做另一件事”。
① 常用结构：主句 + to do sth.（不定式放句末，无逗号）。
I get up early every day to avoid being late for school.
② 强调结构：To do sth., 主句（不定式放句首，后加逗号）。
To relax, Chen Jie plays the flute in her free time.
标志词“in order to”：可加在不定式前（句首或句末），强化目的，句子意思不变。In order to make friends, she joins the music. club.
No.6 作结果状语
常见结构:
"only to do"(常表意外或意外或不愉快的结果)、
"enough to do"(足够......去做)、
"too...to do"(太......而不能去做)
He hurried to the station, only to find the trainhadleft.
他匆忙赶到火车站，结果却发现火车已经开走了。
The box is light enough for me to carry.
这个箱子足够轻，我能搬得动。
No.6 作原因状语
用在表情感、心理状态的形容词(如作原因状语happy / glad等)后，说明情绪产生的原因。
I'm glad to see you. 见到你我很高兴。
She was surprised to hear the news.
听到这个消息她很惊讶。
一用括号内所给词的适当形式填空
1. The neighbour then went to the shop (buy) some vegetables.
2. We are planning to set up an organization named School Watch (make)
sure that students have a safe school environment.
3. She is too young (deal) with such problems.
4. The scientist uses his knowledge to help factories (
produce)better cars.
to buy
to make
to deal
(to) produce
二根据汉语意思完成句子
1.无论大小，只要我们努力去寻找，善良的行为无处不在。
Acts of kindness,big or small, are everywhere if we care them.
2.许多人太在意别人的意见，太努力地取悦别人。
Many people care too much about others' opinions and try too hard
.
3.巧克力曲奇尝起来很甜，它们让我感觉很开心。
The chocolate cookies taste sweet and they make me .
to look for
to please others
feel happy
4.我们经常听见一些学生在英语角练习说英语。
We often hear some students in the English comer.
5.上周我教爷爷如何使用电脑。
I taught my grandfather the computer last week.
practise speaking English
how to use
Thanks !

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