动词不定式是一种非谓语动词形式，其 结构为“to＋动词原形”，其中to不是介词， 而是动词不定式的符号，称为小品词，动 词不定式没有人称和数的变化。动词不定 式和其后面的名词等构成不定式短语，在 句子中可以用作主语、表语、宾语、补足 语、定语、状语等。
To look after my
pets properly takes a lot of time. 一. 作主语： ? To be a doctor is hard.
? To learn English well is not easy.
? 动词不定式短语作主语时，为了避免句子的头重脚 轻，可以用“it”作形式主语，而把真正的主语－动词不定 式短语放在句子的后部。例如上面的句子可以表示为：
It is hard to be a doctor. It is not easy to learn English well. 再如： It’s important to plant trees in spring.
? 如果表示动词不定式的动作执行者，可以在不定式前 面加一个由介词for引导的短语，称为不定式的复合结构。 例： ? It’s good for us to read English aloud in the morning. ? It is important for students to use English every day.
My ambition is to work for firm that develops computer software when I grow up. 二. 作表语： 动词不定式（短语）作表语常用于系词be的后 面。例： His work is to drive a car. My job is to feed animals. Her ambition is to be a doctor.
He hopes to become a teacher.
三. 作宾语 动词不定式（短语）可以放在一些动词后面用作宾语， 能以动词不定式作宾语的动词有：begin, start, want, forget remember, show, learn, like, hate, love, ask等。例： ? I want to tell you a story. ? They begin to work at eight every morning. ? Don’t forget to lock the door. ? Would you like to go and have a picnic with us tomorrow? 注意： （1）如果and连接两个动词不定式，第二个动词 不定式一般省“to”例： He wants to go and have a swim with us. （2）若作宾语的动词不定式（短语）很长，可用it 作形式宾语。 I find it interesting to learn English with you. He found it hard to catch up with others.
The teacher advised him to try another way.
四. 作宾语补足语。例如： ? The teacher asked us to read English for half an hour in the morning. ? The teacher often tells Jim not to spend too much time playing computer games. ? Please let me help you. ? 动词不定式作宾语补足语，表示宾语所做的动作，可 以用动词不定式作宾语补足语的动词有：tell, ask, want, like, invite, encourage, help等。但在let, make, see, watch, hear, feel, notice, have等感官听觉动词或使役动词后面 作宾语补足语的动词不定式一般要省略动词不定式符号 “to”，可以归纳为以下三种句式：
1.不可以省to的不定式作宾语补足语： tell /ask / want / would like / wish / like / invite /encourage /teach sb. to do sth. 例： ? The teacher told us to come earlier tomorrow. ? I want you to go now. ? Her parents wish her to be a teacher. 2.省“to”的不定式作宾语补足语： ? Let / make / have sb. do sth. ? Let the boy go out now. ? The boy made the baby cry. ? see / watch / hear / notice / feel sb. do sth. ? I saw the students play basketball on the playground yesterday ? I often hear the girl sing in the next room. 3.可省可不省的： help sb. （to）do sth. I often help my mother （to）do housework.
?否定形式： （1）动词不定式的否定式是直接在to之前加not. 例：Tell them not to play football in the street. （2）省to的动词不定式的否定式是直接在动词前 面加not. 例： Let the boy not go. ?被动语态： 如果将主动语态变为被动语态时，作宾语补足 语的动词不定式变为主语补足语，动词不定式则 不省“to”，即原来省的再加上，例： ? The boy made the baby cry. ? The baby was made to cry by the boy.
He has a good way to make his classes lively and interesting.
五. 动词不定式作定语 动词不定式作定语常用来修饰名词或不定代词，放于所 修饰的词后，为后置定语。例： ? Who was the first one to arrive? ? She has no paper to write on? ? The best way to learn English is to use it. ? When is the best time to plant vegetables? ? Do you have something to drink? *动词不定式（短语）作定语修饰名词时，与其所修饰 的词具有一种动宾关系，如果不定式中的动词为不及物 动词时，其后应加上一个含义上所需要的介词。例： ? I have no chair to sit on. ? He has no house to live in.
Sometimes too, I was too weak to go to school. 六. 作状语: 动词不定式及其短语具有副词的特性，可在句 中作状语。 （1）作目的状语。如：
He stopped to have a rest.
He woke up to find everybody gone. I’m sorry to hear your grandma is ill.
He is old enough to go to school.
（5）强调动词不定式所表示的目的时，动词不定式可用in order to或so as to +动词原形，so as to不用于句首。如：
The bus stopped so as to pick up passengers.
Wh + to do
七. 不定式和疑问词连用，可以作句子的主语、宾语 表语等。例： ? The problem is where to get a computer. （表语） ? No one knows how to do it. （宾） ? I really don’t know which one to choose. （宾） ? When and where to have the party is not known. (主) *不定式和疑问词连用作宾语时有时可以改为宾语 从句。例： I don’t know what to do next. ? I don’t know what I should do next.
1. Please tell him _______ on the wall. A. don’t draw B. to not draw C. not to draw D. not draw 2. I’d like ________ a word with you. A. had B. having C. to have D. have 3. We often heard him _________ in his room. A. to sing B. sings C. sang D. sing 4. He was made _____ day and night. A. work B. working C. to work D. worked 5. He stopped ______ a look, but saw nothing. A. having B. to have C. have D. had
6. He said he had an important meeting ________. A. attend B. would attend C. attending D. to attend
7. Please give me a piece of paper ________. A. to write B. to write on C. writing D. to write it 8. I don’t know _______. A. what do B. what will do C. what to do D. do what 9. Your radio needs ________. A. to be repaired B. to repair C. repaired D. to repairing 10.Please tell me _____ her. I have something ____ her. A. where to find, telling B. where to find, to tell C. where can find, to tell D. where finding, telling 11.How happy they are ______ each other again! A. to see B. see C. saw D. being seen 12.They decided ____ a letter ______ their thanks. A. to write, expressing B. writing, express C. write, expressed D. to write, to express