不定式是不是都是to do形式的?
好像不是哦~~因为上次我看英语参考答案的时候
它上面竟然注明have being形式也是不定式的一种
怪了~

1)不定式主动形式表示被动意义
英语动词不定式有主动和被动两种形式。当不定式所说明的人或物是不定式所表示的动作的对象，不定式用被动形式。当不定式所说明的人或物是不定式所表示的动作的执行者，即主谓关系时，不定式用主动形式。
但是在某些情况下，不定式虽然与所说明的人或物是动宾关系，仍用主动形式。这种不定式主动形式表示被动意义的情况主要有以下五种：

1. 当不定式与前面的名词有动宾关系，又与句中另一名词或代词构成主谓关系时，该不定式用主动形式表示被动意义。例如：

I have a meeting to attend. 我有会议要参加。（I 与 to attend 有主谓关系）

Give him some books to read. 给他几本书看。（him 与 to read 有主谓关系）
如果不属上述情况，则仍需要用被动形式表示被动意义。试比较下列两句：
①Have you anything to do this afternoon? 你今天下午有事要做吗？
②Have you anything to be taken to the city (by me or someone else)? 你有什么东西要带到城里去吗？
①句中主语 you 与不定式 to do 存在逻辑上的主谓关系，to do 实际上是 you 的动作，所以用主动形式表示被动意义，而②句中主语 you 与不定式用被动形式 to be taken 表示被动意义。

2. 当不定式在 there be 句型中用定语修饰主语而表示被动意义时，一般情况下，既可用主动形式，也可用被动形式。在口语中用主动形式的时候要更多一些。例如：

There is no time to lose/to be lost. 时间紧迫，不能耽搁了。

There are still many things to take care of/to be taken care of. 还有好些事要处理。
但是应该注意以下两点：

(1) 如果不定式结构加了由 for sb 表示的逻辑主语，那么它用主动形式或被动形式必须视sb 是其动作的发出者或承受者而定。例如：

There are still many questions for us to discuss. 我们还有许多问题要讨论。

There are a lot of reasons for the book to be published. 有很多理由应该出版这本书。

(2) 某些动词（常见的有 do 和 see）的不定式作此用法时， 两种形式所表示的意思不同。试比较：

There is nothing to do now. /We have nothing to do now. 现在没事干。

There is nothing to be done now. /We can do nothing now. 现在没什么办法。

There is nothing to see/worth seeing. 没有东西值得看。

There is nothing to be seen/there at all. 看不见有什么东西。

3. 当不定式作表语形容词的状语，又与句中的主语有逻辑动宾关系时，用该不定式的主动形式表示被动意义有以下三种情况：

(1) 形容词说明不定式所表示的动作特征。这类形容词主要有 difficult，hard，east，funny， important，impossible，strange 等。例如：
①Mary is easy to teach. 玛丽容易教。
②He is hard to convince. 他这人很难说服。
③The book is difficult to read. 这本书很难读。
这类句子的主语与不定式结构有逻辑上的动宾关系。因此这类句子可以转换为不定式结构作主语的句子。例如①句可改为“To teach Mary is easy. ”或“It’s easy to teach Mary.”等形式。但要注意，这一句型中的不定式结构不能用被动形式，也不能省略，否则句子的意思就不清楚。

(2) 形容词说明主语的特征，不定式则表示在哪一方面有这种特征。例如：

Not all the food is good to eat. 不是所有的食物都好吃。
The park is very attractive to look at. 这个公园很吸引人。
值得注意的是，上述句型和“Mary is easy to teach.”在形式上虽然相似，但它不可改为不定式结构作主语的句子，句中的不定式省略后，句子意思仍清楚，这是两者的不同之处。

(3) 形容词说明主语的特征，不定式表示由此引起的结果。这类形容词通常和 enough 或 too 连用。不定式可用主动形式，也可用被动形式。例如：

His suitcase is too heavy to carry/to be carried. 他的手提箱重得提不动。

Atoms are too small to see/to be seen. 原子太小，看不见。

This dictionary is cheap enough to buy/to be bought. 这部词典很便宜，能买得起。
但是，当句中加上 for sb，表示不定式的逻辑主语时，则该不定式只用主动形式。例如：

This colour TV set is too expensive for me to buy. 这台彩色电视机太贵了，我买不起。

4. 不定式结构修饰作表语的名词时，如果不定式与这个名词逻辑上有动宾关系，则不定式用主动形式表示被动意义。例如：

This is an easy question to answer. 这是一个容易回答的问题。

It is an important job for us to do. 这是我们要做的重要工作。

This is a difficult sentence to understand. 这是一个难以理解的句子。

5. 少数动词不定式在句子中作表语时，虽与句子主语有逻辑上的动宾关系，但常用主动形式表示被动意义。但这类句子并不多见，有人认为这种不定式结构用法是“古英语的残余”。这类动词主要有 blame，let，do 等。例如：

The house is to let. 房子要出租。

Nobody was to blame for the accident. 这个事故谁也不能责怪。

A lot of things remain to do. 许多事情有待去做。
但是具有对比意义时，仍用被动形式。例如：

The room is to be let, not to be sold. 这个房间只租不售。


She is to be praised, not to be blamed. 她应该受表扬，不应该受责备。

2)不定式是历次大学英语四级考试必考的内容。不定式在句子中可做主语、宾语、表语、定语、状语和宾语补语。

　　1)不定式做主语一般表示具体的某次动作。

　　【例如】

　　To complete the 30storied building in one year was quite a difficult task.

　　To do that implies taking responsibility.

　　当主语较长，谓语较短时，常用it做形式主语，而将不定式放到谓语的后面。

　　【例如】

　　It is important for modern young people to master at least two foreign languages.

　　It做形式主语，不定式放在谓语动词之后常用于下列结构中：

　　a) It is＋形容词(easy, important, difficult, foolish, inconvenient, unnecessary, right, wrong...)＋( for/of sb.)＋不定式

　　【例如】

　　It is essential to reserve a table in advance of Christmas Eve.

　　It is hard to put my hopessintoswords.

　　It is not easy to catch fish with your hands only.

　　It is important for us young people to learn English and master it.

　　b) It is＋名词(a pleasure, a pity, a pleasant thing, one's duty, an honor, a shame, a crime, no easy job...)＋不定式

　　It is a sheer waste of time to read that kind of trash.

　　It is a pity to have to go without her.

　　It is a glorious death to die for the people.

　　c) It takes (sb.) some time (hours, months, days, a lot of time, patience...)＋不定式

　　It takes me three hours to learn English each day.

　　It took them half the night to get home in the snow.

　　2)不定式作表语不定式作表语常表示将来的动作，主语常常是表示意向、打算、计划的词，如wish, idea, task, purpose, duty, job等。

　　【例如】

　　The most important thing for one's health is to have plenty of exercise.

　　My chief purpose has been to point out the difficulties of the matter.

　　The purpose of the organization is to greet all new comers to the city and to provide them with any necessary information.

　　What I wanted was to get the work done as quickly as possible.

　　3)不定式作宾语不定式常在下列动词后面作宾语：

　　afford,agree,apply,arrange,ask,attempt,beg,begin,care,choose,claim,consent,demand,decide,desire,determine,

expect,fail,hope,hesitate,hate,intend,learn,like,manage,mean,neglect,offer,plan,prepare pretend,promise,refuse,resolve,seek,tend,threaten,want等。

　　【例如】

　　I like to go out for walks in the warm sunshine in spring.

　　My mother hates to move from place to place, for she feels tired.I decide to work hard and get doctor's degree.

　　The room is designed to be my study, but now it has to be used as a bedroom for the children.

　　She failed to finish the assignment in time, and she was worried about it.

　　There is a man at the reception desk who seems very angry and I think he means( )trouble. (CET-4 1997, 1)

　　A) making

　　B) to make

　　C) to have made

　　D)shavingsmade

　　mean后面一般加不定式，所以A和D可以排除。根据句意，他看起来非常生气，他想找麻烦，不定式的动作还没有实施，应用一般式，

因此答案为B。不定式作宾语还常用在下面结构中；主语＋动词＋it＋形容词＋不定式。

　　【例如】

　　We found it impossible to get everything ready in time. I think it important to learn English well in college.

使用这种句型的常见动词有：believe, consider, declare, feel, find, guess, imagine, prove, realize, suppose, think,等。

　　4)“whword＋不定式”结构不定式前加一个疑问代词(what, which, who, whom, whose)或疑问副词(where, when, how, why)，

以及连词whether构成特殊的不定式短语，其作用相当于一个从句，这样的不定式短语常在某些动词后面作宾语。

　　常见的可以接这种不定式短语的动词有：

　　know, see, decide, tell,ask,consider,discover,explain,findout,forget,guess,hear,imagine,inquire,learn,observe,

perceive,remember,think,understand,wonder等。

　　【例如】

　　I couldn't decide which book to choose. I can tell youswheresto get this book.They found it hard to decide

whether to go swimming next Sunday or to visit Aunt Sally in New Year.“whword+不定式”结构除了作宾语外，还可以在句中作主语或者表语。

　　【例如】

　　When to start the program remains undecided. The question is how to put the plansintospractice.

　　5)不定式作状语

　　a)不定式作状语表示目的。或用于so as和in order之后，来强调这种目的。

　　【例如】

　　To learn a foreign language well, you must make painstaking efforts.

　　Mother saved every cent she could spare to pay for my schooling.We must develop science and technology at

high speed so as to raise scientific and cultural level of our country.

　　Insgroupsto get a high mark in Band 4, he did a lot of exercises both in grammar and reading comprehension.

　　b)不定式表示结果，特别是在so...as to, such...as to, only to...以及too...to等结构中的不定式表示结果。

　　【例如】

　　I rushed to the station as fast as I could, only to find the train already gone.

　　She left her hometown with her beloved man, never to return.No one is too old to learn.

　　Would you be so kind as to carry the luggage for me?

　　c)不定式常用来修饰形容词，构成下列词组：be able to, be afraid to, be apt to, be bound to, be certain to, be easy to,

be eager to, be fit to, be likely to, be ready to, be sure to, be unable to, be unwilling to, be willing to等。

　　【例如】

　　Chinese team is bound to win the World Cup.

　　It is likely to rain today, for it is very cloudy.

　　I am willing to help you with your homework, for we are friends.

　　6)不定式作宾语补语不定式常跟在下列动词之后作宾语补语：ask, advise, allow, beg, cause, compel, command, enable, encourage,

expect, feel, force, find, hear, have, inform, invite, let, make, mean, notice, order, permit, persuade, remind, require, request,

teach, tell, urge, watch, warn, watch等。

　　【例如】

　　Because of the complexity of the modern equipments, most offices require secretaries to have specified training.

　　He asked you to call him at ten o'clock.

　　The note reminds me to be careful whatever I do.

　　I'd never allow my children to behave like that.

　　当不定式在let, make, have, hear, look at, listen to, feel, observe, watch, notice, perceive(感觉到)等动词后面作宾语补语时，

不定式不带to.

　　【例如】

　　Whenever something is wrong with you, please do let me know.

　　I will have the students write a passage about Internet.

　　I saw my mother shed tears at the news that the neighbor girl got seriously hurt in a car accident.

　　It seemed so long before he heard the stone hit the water.

　　7)不定式作主补带有宾语及宾语补足语结构的动词变为被动语态时，原来的宾语变为主语，宾补则变为主补。加主补的动词主要有：assume, believe,

know, report, say, suppose等。

　　【例如】

　　Mr. Brown is said to have left for Italy last week.(It is said that Mr. Brown left for Italy last week.)

　　Persons have been said to climb on roofs, solve mathematical problems, compose music, walk through windows and commit murder

in their sleep.

　　He is reported to have won the 100meter running race in the Olympic games.

　　8)不定式作定语

　　a)不定式作定语通常要放在其所修饰的名词或代词之后。

　　不定式常作下列的名词定语：attempt, ability, anything, chance, desire, determination, decision, effort, failure, intention, need,

opportunity, plan, promise, pressure, right, tendency, time, way等。

　　【例如】

　　His efforts to carry out the plan were successful.I have no intention to go to the cinema with you.

　　There is no need to bother him with such trifles.

　　There is a tendency to writer quite long sentences in commercial correspondence.

　　The pressure( )causes Americans to be energetic, but it also put them under a constant emotional strain. (CET-4 1997,6)

　　A) to compete

　　B) competing

　　C) to be competed

　　D)shavingscompeted

　　pressure后面应接后置定语，表示竞争的压力。单个分词作定语一般置于名词前，故B和D可以排除。C为不定式的被动式，而竞争和压力之间没有被动关系，

因此正确答案为A。特别注意的是在不定式与其修饰的名词有动宾关系时，要根据句子的需要在不定式后加适当的介词，这个介词的选用取决于被修饰的名词或不

定式本身的要求。

　　【例如】

　　She is a very nice person to work with.

　　This is an important issue to talk about.

　　b)由only, last, next,序数词或形容词最高级修饰的名词常用不定式作定语。