Grammar: 动词不定式
Ⅰ. 不定式句法功能
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
生词表: