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动词不定式
一、学习目标
1.掌握不定式的概念和基本用法
2.掌握不定式在句中的作用
3.掌握不定式的重要句型
二、知识讲解
（1）动词不定式的基本概念
动词不定式的基本形式是 to + 动词原形，有时可不带to。
（2）动词不定式的基本用法
1. 动词不定式没有人称和数的变化。
2. 动词不定式在句子中可以担任除了谓语之外的任何成分。
观察句子，写出不定式所做的成分
1. To grow more trees here is very important.
2. To think carefully before you act is necessary.
3. To walk to school takes me twenty minutes.
所作成分：
句型转化：
1. To grow more trees here is very important.
=It’s very important to grow more trees here.
2. To think carefully before you act is necessary.
=It’s necessary to think carefully before you act.
3. To walk to school takes me twenty minutes.
=It’s twenty minutes to walk to school.
注意：It’s … to do 句型： It 作形式主语， 真正的主语是不定式。
观察句子，写出不定式所做的成分
1. His wish is to become a scientist.
2. Our duty is to protect the environment.
3. The first important thing is to save their lives.
所作成分：
注意：当不定式作主语的句子中又有一个不定式作表语时， 不能用It is… to do的句型。例如：
To see is to believe. 百闻不如一见。
观察句子，写出不定式所做的成分
1. She wanted to get home earlier that day.
2. They refused to do so.
3. I hope to visit my grandparents soon.
所作成分：
注意：不定式用在及物动词后，担当宾语。常见的及物动词有：
观察句子，写出不定式所做的成分
1. I asked him to help us.
2. The soldiers forced us to open the door.
3. They encouraged him to work hard.
所作成分：
观察句子，写出不定式所做的成分
1. He got up early to catch the train.
2. He came to give us a talk yesterday.
3. I went to a park to breathe the fresh air.
所作成分：
注意：针对”why…?”（为什么……呢？）的疑问句作答时 一般来讲，用because…（因为……）回答，表明其理由、原因。但当回答表示目的“为了……”时，可用不定式代替作简略回答。
例句A: Why did you go to the library?
B: To study English.
A: Why does Mary get up early every morning?
B: To catch the first bus to school.
观察句子，写出不定式所做的成分
1. I am glad to be here.
2. I am sorry to trouble you.
3. We were surprised to find him there.
所作成分：
注意：不定式放在glad，happy，sorry之类的表达感情、情绪的形容词后面来修饰该形容词，表示“因为……而……”的意思。
如：
Be glad + to do sth. 很高兴……
Be happy + to do sth. 很高兴……
Be sad + to do sth. 很悲伤……
Be sorry + to do sth.很抱歉、遗憾……
Be stupid + to do sth. 很愚蠢……
另外，有些由过去分词转化为形容词的句型也经常使用：
Be interested + to do sth. 很感兴趣……
Be satisfied + to do sth. 很满意……
Be surprised + to do sth. 很惊讶……
Be worried + to do sth. 很担心……
观察句子，写出不定式所做的成分
1. Mr. Wang is a man to believe in.
2. The boy found no one to play with.
3. I have an important meeting to attend.
所作成分：
注意：不定式有时起形容词作用，修饰名词或代词，在句中担任定语。不定式作定语时，它的位置在它所修饰的名词或代词之后。
例句： I have some books to give you.
如果不定式是不及物动词或者不定式所修饰的名词或代词是不定式动作的地点，工具等，不定式后面就应带必要的介词。
例句:
They have a lot of things to talk about.
There is nothing to worry about.
He is looking for a room to live in.
不定式修饰something, anything, nothing时，放在它们的后面。如果something, anything, nothing用形容词来修饰，那么词序应该是：
something
anything + 形容词 + 不定式 + ……
nothing
例句：
Please give me something hot to drink.
I need something nice to wear to the party next weekend.
（3）不定式的重要句型
1.不定式的否定式和有关ask的句型
不定式否定式句型是“not+不定式”，经常用在ask/tell sb.(not) to do sth中。
例句：The teacher told us not to stop writing.
He asked me not to open the window.
(He didn’t ask me to open the window.)
2. “疑问词 + 不定式”的用法
不定式可以和疑问代词who, what, which及疑问副词when, how, where连用，构成不定式短语，在句中担当主语、宾语、表语等成分。
例句：I know how to cook.
I don’t know what to buy for you.
What to d
