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1、动词不定式动词不定式由“to+动词原形”构成，在某些情况下不带to，在句中可以作主语、表语、宾语、宾语补足语、定语、状语等成分，动词不定式有时态和语态的变化。1. 动词不定式的句法功能1) 作主语（可用形式主语it）E.g.: To protect environment is every citizens duty in a way. 从某种意义来讲，保护环境是每个公民的责任。 To see is to believe. 眼见为实。 Is it necessary to complete the design before National Day? 有必要在国庆节前完成这项设计吗？ It
2、is hard for strangers to find the way. 对于陌生人来说找到这条路很难。 It is really kind of you to help me. 你帮我真是太好了。 (It is + kind, wise, clever, foolish, right, wrong, careful, careless, polite, impolite + of sb. to do sth.) with him is a great pleasure. A. To talk B. Talk C. Talked D. To talking2) 作表语（说明主语的内容）E.
3、g.: Her wish is to become a college student. 她的愿望是成为一个大学生。注意：a.若主语和表语都是不定式，前者为条件，后者为目的或结果。E.g.: To learn a language is to use it. 学英语就是要使用它。 b.动词不定式作表语时，主语经常是dream, plan, wish, business等误区警示：动词不定式和动名词都可做主语和表语。一般来说，表示比较抽象的一般行为多用动名词；表示具体的某次动作，特别是将来的动作时，多用动词不定式。有时两者可以互换。3) 作宾语（有些动词一般用不定式做宾语，如：want, wis
4、h, agree, decide, pretend, ask, promise, plan, offer, learn, refuse, fail, manage, hope, afford, begin, expect, hesitate, prepare, threaten, bother, undertake, care, demand, fear, intend, attempt, choose, desire, hate, volunteer, beg, claim, prefer, start等）E.g.: We agreed to meet here, but so far he
5、 was not turned up yet.我们同意在这见面，但他到现在为止都没有露面。【助记】三个希望两答应: hope, wish, want, agree, promise两个要求莫拒绝:demand, ask, refuse设法学会做决定:manage, learn, decide不要假装在选择:pretend, choose注意：作宾语时如果还带有宾语补主语，往往把不定式放在补足语之后，而用it作形式宾语。E.g.: I find it interesting to study English. 我发现学英语很有趣。I didnt it until you had explaine
6、d now.A. manage to do B. managed to do C. manage to have doing D. manage doing4) 作宾语补足语（变成被动语态时作主语的补足语）E.g.: The doctor warned the patient not to eat oily food after the operation. 医生告诫病人手术后不要吃油腻的食物。注意：不定式作宾语补足语省略to的情况有下列口诀：五看三使役两听一感半帮助。但是这些句子如果变成被动结构时，就必须带上to:五看：watch, see, notice, look at, observe
7、三使役：make, let, have两听：listen to, hear一感：feel半帮助：help5) 作定语（动词不定式放在被修饰名词的后面）i. 动词不定式作定语与修饰的词之间有三种关系，即主谓、动宾与同位关系。E.g.: He is always the first to come and the last to leave.（主谓关系）他总是第一个来，最后一个走。I have a lot of marks to sell. （动宾关系）我有很多面罩要出售。We all have a chance to go to college. （同位关系）我们都有上大学的机会。ii. 动词不
8、定式与被修饰的名词存在被动关系时，动词不定式的动词必须是及物动词，如果动词不定式的动词是不及物动词，则后面必须要有适当的介词。E.g.: I have no jewelry to wear. 我没有首饰戴。 There is no one to take care of. 没有人需要照顾。学法点拨：a.被修饰的名词前有序数词、形容词最高级或next, second, last, only, not a和the等限定词时，只能用动词不定式修饰。 E.g.: I am the only one to come. 我是唯一一个要来的。 b.不定代词something, nothing, little
9、, much, a lot等习惯上用动词不定式作定语。 E.g.: I have nothing to say on this question. 在这个问题上，我没有什么话要说。 c. 如果其动词要求用动词不定式作定语，或者其形容词要接动词不定式作补语，则相应的名词一般用动词不定式作定语。 E.g.: tend to do = tendency to do decide to do = decision to do be curious to do = curiosity to do Their decision to give up the experiment surprised us.
10、 他们放弃这个实验的决定使我们大吃一惊。6) 作状语（可表目的、结果、原因等）i. 表目的A. 动词不定式to do直接作目的状语E.g.: We work hard to be admitted into a key university.我们为了被重点大学录取而努力学习。B. In order to do作目的状语，可以位于句首、句中E.g.: In order to finish his work on time, he worked like crazy.=He worked like crazy in order to finish his work on time. 为了准时完成他
11、的作品，他像疯了似的工作。C. So as to do作目的状语，不可位于句首E.g.: We will hold a meeting in order to explain the programme.=We will hold a meeting so as to explain the programme.=We will hold a meeting to explain the programme.=In order to explain the programme we will hold a meeting.=To explain the programme, we will h
12、old a meeting.我们会举行一场会议去解释这个项目。注意：当不定式作状语放在句首时，不定式的逻辑主语要与句子的主语一致。学法点拨：so that与in order that可以引导目的状语从句，相当于so as to和in order to do充当的目的状语，从句中常带有may, might, can, could, would, should等情态动词。 E.g.: We will hold a meeting in order that we can explain the programme. =We will hold a meeting so that we can ex
13、plain the programme.ii. 表示结果A. only to do常表示出乎意料的结果E.g.: He lifted a rock only to drop it on his feet.他举起了一块儿石头却砸在了自己脚上。I hurried to the station only to find that the train had left.我匆忙赶到车站却发现火车已开走了。B. enough to do ；too to do; so as to do; such as to do结构中，to do表示结果E.g.: He didnt run fast enough to
14、catch this train. 他跑得不够快不能赶上这列火车。 It is too cold for you to work outside. 对你来说在外面工作太冷了。 The girl was so kind to help the old man off the bus. 这个女孩热心的帮助老人下车。 I am not such a fool to believe him. 我不会笨到去相信他。学法点拨：a. so that ； such that引导结果状语从句，意为“如此以至于”so为副词，修饰形容词或副词；such为形容词，修饰名词。 b.在so that引导的结果状语从句中，“so + adj./adv.”置于句首时，主句用部分倒装结构。 E.g.: So loudly did he speak that everyone could hear him clearly. 他讲的如此大声以至于每个人都可以很清楚的听到。 c. 现在分词（短语）作结果状语，表示自然而然的结果；动词不定式（短语）作结果状语，表示意料之外的结果。iii. 表示原因（通常用来表示情绪方面的）A. 动词不定式to
