1. 作主语：The cat said, “To take roller coaster” is terrible.
不定式短语作主语时，可以直接放在句首，但在很多情况下，尤其是在疑问句和感叹句中，往往放在谓语之后，而用先行代词it作形式主语。
→ The cat said, “It’s terrible to take roller coaster.”
How long did it take you to take roller coaster?
How terrible it is to take roller coaster?
不定式作主语常见句型：
a) It is + adj. (easy, important, difficult…) + 不定式
b) It is + n. (a pity, a pleasure, one’s duty, a shame) + 不定式
eg. It’s my duty to teach you how to be a student of No.3 Middle School.
c) It takes/needs/requires + some time (hours, months, days, patience…) + 不定式
eg. It requires patience to be a good teacher.
2. 作表语：当句子的主语是aim, idea, policy, question, suggestion, wish, task, duty, job, purpose等或者主语是what引导的名词性从句时，后面可以用不定式做表语，用以说明主语所包含内容。
eg. Our most important task now is to make a plan.
注：作表语的不定式都带to，但当主语部分有实义动词do时，to可以省略。
eg. The only thing we can do now is wait and see.
3.作宾语
The cat said “Remember not to take it next time!”.
a) 可以直接用不定式作宾语的动词很多，常见的有：agree, afford, tend, ask, decide, determine, expect, fail, hope, learn, intend, manage, offer, plan, promise, refuse, want, wish等
2005年天津卷12题：I don’t want _____ like I’m speaking ill of anybody, but the manager’s plan is unfair.
A. to sound B. to be sounded C. sounding D. to have sounded
当不定式短语比宾补长时，往往将不定式放到宾补后，而用先行代词it作形式宾语，常用动词有feel, think, find, believe, consider, make等。
The cat felt it terrible to take roller coaster.
b) 不定式一般不作介词的宾语，只有少数介词如but, except等后面可以跟不定式作宾语。一般情况下作介词宾语的不定式都带to，如果but或except所在句子里的谓语动词都是实义动词do, does, did时，通常省略to。
Eg. We have no choice but to wait.
Cf. We can do nothing but wait.
4. 宾语补足语
在SVOC句型中，许多动词都可以按不定式作宾语补足语。
a) 通常作宾语补语的不定式要带to，常用于以下动词之后：ask, tell, advise, allow, enable, expect, force, get, like, order, teach, want, invite, wish, beg等
You should get them to help you.
但在谓语动词believe, find, think, feel, consider, suppose, imagine, prove等后面跟to be…作宾补，不跟to do…
eg. They believe him to be honest.
b) 以下两类动词后跟不定式作宾补时不能带to
①一些表示“致使”意义的动词，如：let, have, make等
②一些表示感觉的动词，如：hear, feel, see, watch, notice等
Don’t let the children trouble you.
I heard someone open the door.
但当这两类动词为被动态时，不定式就成了主补。作主补的不定式必须加上to
His father made him go to bed early.
→He was made to go to bed early by his father.
5. 作定语
不定式可以在句子充当后置定语，修饰名词。
以下几类情况常用不定式作定语：
①能带不定式作宾语的动词，其同源名词可以带不定式作定语。常见的有attempt, decision, promise, plan等
eg. He hasn’t kept his promise to write to his parents regularly.
②常与不定式搭配的形容词，其同源名词一般可以用不定式作定语。常见的有ability, determination, anxiety, eagerness等
eg. His eagerness to finish his homework was quite clear.
③序数词形容词最高级或被only, last, next等修饰的名词可以用不定式作定语：
She was the only person to survive after the earthquake.
Tips: 不定式在作定语时，有时与被修饰的名词有意义上的主谓关系、同位关系、动宾关系，如果该不定式是不及物动词，它后面需要加上适当介词。
Eg. He’s always the first to come and the last to leave. 主谓关系
I’ve no time to listen to your excuse. 同位关系
She has a meeting to attend. （动宾关系=attend a meeting）
There’s nothing to worry about. (动宾关系=worry about nothing)
6. 作状语
不定式可以作状语，表示目的、结果、原因、条件等。
①to…, in order to …, so as to …(不能放在句首)作目的状语
2005年辽宁卷22题：All these gifts must be mailed immediately _____ in time for Christmas.
A. in order to have received B. in order to receive C. so as to be received D. so as to be receiving
②在so…as to, such….as to, only to …结构中不定式作结果状语，其中only to…用于表示意想不到的结果。
He hurried to the station only to find the train had gone.
③enough to, too…to结构
eg. The boy isn’t old enough to go to school.
= The boy is too young to go to school.
④形容词（happy, glad, lucky, fortunate, surprised, angry, anxious, ready, quick, slow, cruel, clever等）+ 不定式结构
eg. I’m glad to meet you.
The question is different to answer.
He is hard to get along with.
7. 作插入语，用来说明说话人的态度、看法、对整个句子进行解释，如to be frank（坦白地说），to be sure（确实）等。
Eg. To tell you the truth, I hate you.
8. 作同位语
eg. The order to start the general attack soon came.
不定式的复合结构，以it为形式主语或形式宾语引导的复合结构，如果其前的形容词是指行为的性质就用：for sb. to do sth.这种复合结构在句中可作主语、表语、宾语、定语、状语等。
It is necessary for me to learn English well.
如果该形容词是指行为的性质，同时又指行为的人，则用of sb. to do sth.。这种句式中的常用形容词有：right, wrong, brave, careful, careless, clever, wise, stupid, cruel, foolish, good, honest, kind, nice, silly等。
eg. It’s very kind of you to come to see me.
连接代（副）词+不定式（包括whether, what, which, whom, where, when, how, 不包括why），在句中起名词的作用，通常跟在诸如tell, know, show, decide, learn, wonder, explain等动词后作宾、主语或表语。
Eg. No one can tell me where to find John.
When to the exam is still unknown.
The problem is how to get enough money.
不定式的进行式、完成式和被动式
①不定式的进行式由to be + V-ing构成，用来表示谓语动词动作发生时，不定式的动作正在进行。
Eg. Some students pretended to be reading English when the teacher came in.
②不定式完成式由to have + V-ed构成，用来表示动作发生在谓语动作之前。
Eg. 2005年江苏卷No.25
--- Is Bob still performing?
--- I’m afraid not. He is said _______ the stage already as he has become an official.
A. to have left B. to leave C. to have been D. to be left
答案是A
③不定式的被动式分为一般式被动to be V-ing和完成式被动to have been V-ed。当不定式的逻辑主语是不定式所表示的动作的承受者时，不定式要用被动语态。
Eg. It is an honour for me to be invited to the party.
The book is said to have been translated into many languages.
2005年辽宁卷No.22
All these gifts must be mailed immediately _____ in time for Christmas.
A. in order to have received B. in order to receive C. so as to be received D. so as to be receiving
动名词
1. 动名词的句法功能：动名词由动词加ing构成，与现在分词的形式相同。动名词主要起名词作用，在句中担任主语、表语、宾语和定语。
①作主语，可以直接放在句首，也可以用先行代词it作为形式主语，而把动名词后置。
eg. Seeing is believing. (眼见为实)
Saying is easier than doing.
Collecting stamps is a good hobby. (单个动名词短语作主语时，动词用单数)
动名词作主语还有以下两个习惯表答法：
It is no use (good) + 动名词：做某事没有用
Eg. It’s no use crying over spilt milk. (覆水难收)
There is no + 动名词 (= It is impossible to do sth.)
Eg. There is no knowing what may happen.（未来的事无法知道）
②作表语：通常是说明主语的内容，注意它与谓语动词进行时的区别
eg. His hobby is collecting stamps. (此句为SVC结构) 可改为：Collecting stamps is his hobby.
Cf. He is collecting stamps. (is collecting是谓语动词进行时，此句为SVO结构)
不能改为：Collecting stamps is he.
③作宾语
A. 作及物动词 的宾语(enjoy, mind, finish, appreciate, avoid, consider, delay, escape, pratise, suggest, keep(on), miss)
eg. 2005年上海卷No.32
He got well-prepared for the job interview, for he couldn’t risk _____ the good opportunity.
A. to lose B. losing C. to be lost D. being lost
答案为B
有些动词（attempt, begin, continue, hate, like, love）后面既可以接不定式作宾语，也可以接动名词作宾语，意义差别不大。通常认为用动名词泛指一般的倾向性，用不定式则表示特定或具体某一种动作。
Eg. I like swimming but I don’t like to swim in winter.
动词prefer后面接不定式作宾语时，句子结构与按动名词作宾语是不一样。
eg. I prefer to drive rather than to be driven.
I prefer driving to riding.
有些动词，如forget, remember, regret等，后面接动名词表示的动作先于谓语动词动作，不定式表示的动作后于谓语动词。
Eg. 2005年北京卷No.30
When asked by police, he said that he remembered _____ at he party, but not ______.
A. to arrive, leaving B. to arrive, to leave C. arriving, leaving D. arriving, to leave
在下列句型中动名词作真正宾语：
动词+it（形式宾语）+宾补+动名词（真正宾语）
eg. I think it no use telling them.
We think it no good inviting to him.
B. 作介词的宾语
Eg. 2005年浙江卷No.3
The president spoke at the business meeting for nearly an hour ______ his notes.
A. bringing up B. referring to C. looking for D. trying on
be used to doing 习惯于做；look forward to doing 盼望做；devote one’s life to doing 致力于做；spent time (in) doing 花时间做；be fond of doing 喜爱做；be good at doing 擅长做；be proud of doing 为做…而自豪；be tired of doing 对做…感到厌倦；feel like doing 欲想做； go on doing 继续做（原来的事）；keep on doing 不停地做；what about doing 做…怎么样；think of doing 考虑做；be interested in doing 对做…感兴趣；have some difficulty/trouble (in) doing 做某事有困难；be busy (in) doing 忙于做；instead of doing 做…而不做…
eg. 2005年江苏卷No.23
Everybody in the village likes Jack because he is good at telling and ______ jokes.
A. turning up B. putting up C. making up D. showing up
答案为C
④作定语
动名词可作前置定语，表示所修饰的词的用途或目的，可用for改写；而现在分词作定语时，可用定语从句改写。
swimming pool waiting room walking stick
a sleeping car=a car for sleeping a sleeping child= a child who is sleeping
⑤作同位语
eg. That’s the queen’s full-time job, laying eggs. 这就是蚁后的专职工作??产卵。
2．动名词的逻辑主语
①人称代词做逻辑主语时应用所有格，即形容词性物主代词。
Eg. Do you minding my smoking here?
②逻辑主语是不定代词或指示代词时，很少用所有格，而用普通格。
Eg. He was awakened by someone knocking the door.
There’s no need for that being done.
③逻辑主语是名词时，用所有格，但是如果名词为无生命物体时，则用普通格。
Eg. Mary’s laughing made Tom angry.
There is no hoping of the factory making profit.
④在口语中，动名词如果不在句首，可以用名词普通格或人称代词宾格作逻辑主语。
Eg. 2005年安徽卷No.34
I really can’t understand _____ her like that.
A. you treat B. you to treat C. why treat D. you treating
3. 动名词的完成式、一般式被动和完成式被动。
Eg. After having finish his work, he went home.
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