导图社区 英语动词不定式
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英语动词不定式
最完整的英语动词不定用法。包含动词不定式（短语）作主语、动词不定式（短语）作表语、动词不定时（短语）作宾语等。
编辑于2021-08-23 22:02:09
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动词不定式
1. 概述
在英语中，不是用作句子谓语，而是用于担任其他语法功能的动词，叫做非限定动词（The Non-Finite Verbs）。非限定动词有3种形式：不定式（The Infinitive）、分词（The Participle）和动名词（The Gerund）。
动词不定式由不定式符号“to（小品词）+动词原形”构成（有时不带to）。它不能单独作谓语，不随主语的人称和数的变化而变化，具有名词、形容词和副词的特征。但它还保留着动词的特征，可以和半助动词或情态动词连用构成复合谓语，可以有状语修饰, 如果是及物动词，可以带宾语。动词不定式连同它的宾语、状语等一起构成短语，称为不定式短语（The Infinitive Phrase）。不定式短语可在句中作主语、表语、宾语、定语、状语、宾语补足语和主语补足语。如：
To master English gives us much help in the study of science.在科学研究中，掌握英语会给我们很大帮助。（主语）
It is easy to open a shop but hard to keep it always open.〈谚〉创业容易，守业艰难。 （主语，It为形式主语）
To know how to wait is the great secret of success. 〈谚〉成功的重要秘诀是懂得如何去等待。（To know how to wait 为主语）（how to wait 为宾语）
He that stumbles twice at the same stone deserves to have his skin broken.〈谚〉不吸取教训者活该倒霉。（宾语）
We can do nothing except wait.我们只能等待。（介词宾语）
He that knows when to speak, knows too when to be silent. <谚>该讲就讲，该沉默就沉默。（宾语）
The first step towards greatest is to be honest.〈谚〉诚实是迈向伟大的第一步。（表语）
The best way to know a friend is when you are penniless and frustrated.〈谚〉驰骋识骏马，患难见真情。/患难之交为挚友。（定语）
I went all the way to see them but they were out.我走老远去看他们，他们却出去了。 （目的状语）
She was wrong not to attend the meeting.她不参加会议是错误的。（原因状语）
I worked hard only to fail at last.我学习努力，只是最后未及格。（结果状语）
This book is small enough to put in your pocket.这本书很小，可以放进口袋里。（程度状语）
I advised him to try the medicine.我劝他试试这种药。（宾语补足语）
I will not let such an opportunity slip.我决不会错过这种机会。（宾语补足语）
My brother was told not to write on the wall.告诉我弟弟不要在墙上乱涂写。（主语补足语）
动词不定式的否定式通常由“not +不定式”构成。如：
It's a mistake not to follow the natural rule.不遵守自然法则是错误的。（主语）
I hope not to keep you waiting long.希望没让你久等。（宾语）
He studied hard so as not to be degraded from the class.为了不降级，他努力学习。（目的状语）
有时在不定式前加never，构成不定式的否定式。如：
She promised never to be late again.她许下诺言再也不迟到。
You seem never to think of yourself.你似乎从不考虑自己。
应注意在同一个句子里，用不定式否定式和句子谓语动词的否定式意义不同。如：
a
I wasn't anxious to go there.我并不急于要去那里。
I was anxious not to go there.我希望不要去那里
b
I am not at all surprised to hear of his failure.听说他失败了，我一点也不感到吃惊。
I am surprised not to see all that before.我很吃惊从前竟然没有看到这一切。
由于动词不定式保留着动词的特征，所以它可以有宾语，可以用状语修饰。如：
We need you over to help me with the children.我们需要你过来帮我照看孩子。
She asked you to telephone or wire her on Monday.她请你于星期一给她打电话或电报。
Liquids have a tendency to expand and contract in much the same way as gases.与气体一样，液体也会膨胀和收缩。
在带to的不定式中，通常to和其后边的动词是不分开的。但是偶尔将一个副词插入其间，这种情况称为分裂不定式（Split Infinitive）。如：
He stayed at the office to finally check the accounts.他留在办公室最后检查账目。
He failed to entirely understand the importance of this question.他并未完全理解这个问题的重要性。
You are to please come over here.请你至U这边来。（= You are to come over here, please. /You are to, please, come over here, please = if you please 作插入语）
2. 动词不定式的句法作用
1. 动词不定式（短语）作主语
动词不定式（短语）作主语时，一般表示具体的、个别的、一次性的或具有将来意味的动作。在表示一般抽象概念时多用动名词（短语），但有时也用不定式（短语），二者可以互换使用。如：
To read /Reading good books makes him happy.读好书使他快乐。
动词不定式（短语）作主语时，谓语动词通常用单数，其句型有4种。
1. 动词不定式（短语）+ v. +其他成分
在这种句型中，作主语的动词不定式（短语）直接位于句首，如：
To read without reflecting is like eating without digesting.〈谚〉读书不思考，好比吃饭不消化。
To master a foreign language requires painstaking effort.掌握外国语需要下苦功夫。
To make your children capable of honesty is the beginning of education.〈谚〉教孩子诚实是教育之始。
To wait for luck is the same thing as waiting for death.〈谚〉等待走运无异于等待死亡。
2. It +v.+宾语/表语+作主语的不定式（短语）
在这种句型中，位于句首的It是形式主语，真正主语是位于句子后部的动词不定式 （短语）。其句型有4种：
(1)“It + v. + 宾语 / 表语 + to do sth.” :
It needs greater wisdom not to play the fool.〈谚〉不当傻瓜就得有才智。
It takes ten years to grow trees, but a hundred to rear people. ( →It takes three generations to make a gentleman.)〈谚〉十年树木，百年树人。
It makes me sick to think about it. 一想到它我就恶心。
It does you a lot of good to swim in rivers, lakes and the sea.在大江、大海里游泳有好处。
It is difficult to imagine the modern world without oil.很难以想象没有石油的现代世界(的情景)。
It is wise not to seek a secret, and honest not to reveal it.〈谚〉不探寻隐私为明智，不泄露隐私为诚实。
It was against all my principles to work with them.与他们共事完全违背我的原则。
It was not within my power to answer the question.回答该问题不属我的职责范围。
It was quite beyond me to help them.帮助他们完全不是我能解决得了的。
It is a great ability to be able to conceal one's ability.(谚〉大智若愚。
It is a great honour to hear you speak so highly of me.听到你这么夸奖我真是莫大的荣幸。
It is hard task to break up long habit in a short time.〈谚〉旧习难改。
(2)“It + v. + 宾语 / 表语 + for sb. to do sth.":
Ifs the easiest thing in the world for man to deceive himself.〈谚〉自欺乃世上最易之事。
What a relief it is for us to succeed in our experiment at last!我们的实验终于成功了，这对我们真是一个极大的安慰！
It is important for a scientist to look at matter from the viewpoint of movement.科学家要以运动的观点看待事物是很重要的。
It was hard for him to live on his small pension.依靠他那点养老金维持生活很难。
(3)“It + v. + 表语 + of + 名词 / 代词 + to do sth.” :
It's very thoughtful and kind of you to offer me this lovely holiday.你给我提供了这么好的假期，谢谢你的关心和好意。
It was careless of you to leave your umbrella in the train.你真粗心，把伞忘在火车上。
It was kind /polite of Harry to give up his seat in the bus to the old woman.哈里真有礼貌，在公共汽车上把座位让给那位老太太。
【注释】
for...to结构和of...to结构的区别用法请参见7.7.4不定式复合结构。
(4)“It + Vi + to do sth.” :
It pays to read this novel.这本小说值得一读。
=It is worthwhile to read this novel.
= This novel is worth reading.
= This novel is worthy of being read.
= Reading this novel is worthwhile.
= Reading this novel is worth our while.
It won't do for us to be late.我们退到是不合适的。
It only remains to wish you both happy.最后谨祝您二人幸福。
【注释】
以it作形式主语常见的8种形式：
①It is + adj. + to do sth.
It is hard /easy /difficult /important /necessary /foolish /unwise /right /wrong /nice to do sth.
②It is + n. + to do sth.
It is a pleasure /pity /shame /pleasant thing /an honor /one's duty to do sth.
③It requires hard work /courage /patience to do sth.
④It feels /sounds /seems /appears good to do sth.
⑤It made one excited /laugh to do sth.
⑥It takes three hours /no time /a lot of time /patience to do sth.
⑦It（ only ）remains to do sth.尚须，还需，有待于，待留
⑧It does not /won't /would not do to do sth.不可以做，做…不合适，做…行不通
3. "how /what /when /where /which /why + 不定式（短语）”作主语
本结构作主语相当于名词作主语，句中谓语多用被动式或系表结构。如：
When to start remains undecided.出发时间尚未定。
Where to hold the meeting is still unknown.会议地点还未通知。
How to solve the problem has not been decided yet.如何来解决这个问题还未决定。
What to do with her must be quickly decided.怎么处理她必须赶快做出决定。
4. “for there to be + n."结构作主语
本结构作主语时，可用it作形式主语，for there to be作真正主语，也可直接位于句首作主语。如：
In such cases it is impossible for there to be an escape of air from the container.在这种情况下，不存在空气从容器里逸出的可能。
It's essential for there to be more houses built next year.明年建更多的房子是必要的。
For there to be so few people in the streets was unusual.大街上行人如此少实在罕见。
2. 动词不定式（短语）作表语
动词不定式（短语）作表语主要有3种句型：
动词不定式（短语）直接作表语
动词不定式（短语）作表语相当于名词作表语，它和主语处在同等地位。它所指的或是和主语一样的东西，或是主语所产生的结果。常常可以将主、表交换位置，句子的意义不变。如：
Our task now is to catch up with and surpass the world's advanced levels.我们现在的任务是赶上并超过世界先进水平。
The greatest test of courage on earth is to bear defeat without losing heart.〈谚〉世间勇气的最大考验乃是容忍失败，决不丧志。
The masterpiece of man is to live to the purpose.〈谚〉人之杰作是生活有道。
如果句子的主语和表语都是表示动作的词，通常二者都用不定式或都用动名词。如：
To ask well is to know much.〈谚〉善问懂得多。
To save time is to lengthen life.（谚〉节约时间就是延长寿命。
To change is to make efforts to deal with difficulties.变革就是努力去解决困难。
在这种句子中，如果主语是动名词，表语也用动名词，而不用不定式。如：
Seeing is believing. = To see is to believe.眼见为实。（一般不说:* To see is believing.）
Teaching is learning.教学相长。
动词不定式作表语一般带to,但如果主语部分有实义动词do,可以带to,也可以省略to。 如:
What he wanted to do was （to） wash his hands of it.他打算不再参与此事。
The only thing you can do is （to） wait and see.唯一你能做的是等着瞧。
【注释】
be用作助动词时，可以和不定式连用构成复合谓语。其详细用法请参见助动词相关内容。
"how /what /when /where /which /why + inf. phr.n 结构作表语
The question is how to improve ourselves in English.问题是如何提高我们自身的英语。
The problem is where to find the answer.问题是到哪里去找答案。
The point is what to do and why to do it.问题是做什么，为什么做。
The question is when to finish the experiment.问题是什么时候完成实验。
The difficulty is which one to give the reward to.困难是奖赏谁。
for there to be + n.结构作表语：
What John was waiting for was for there to be complete silence.约翰等待着要大家完全安静下来。
3. 动词不定式（短语）作宾语
动词不定式作宾语时，一般表示特殊的、具体的、一次性的行为。其句型有5种。
动词不定式（短语）直接作及物动词的宾语
以不定式做宾语的动词常见的有afford, agree, aim, apply, arrange, ask, attempt, begin, care, choose （宁愿，偏要），claim, consent （答应，同意），continue, dare, decide, decline （谢绝），demand, desire, determine, elect, endeavour, expect, foil, forget, guarantee, hate> help, hope, intend, learn, like, manage, mean, need, offer, plan, pledge （发誓；保 证），prepare, prefer, pretend, profess （声称），promise, refuse, remember, require, resolve, seek, start, swear, threaten, try, undertake， venture, volunteer, vow （誓约），want, wish 等。 其句型有两种：
subj. + vt. + to do sth.:
You can't afford to pay such a price.这样的价钱你付不起。
Harry aims to become a computer expert.哈里的目标是成为一名计算机专家。
I must ask to be excused.我必须请求原谅。
We must continue to increase production and practice economy.我们必须继续增加生产，厉行节约。
She declined to have lunch with her friend, saying that she wasn't feeling well.她婉言拒绝了同朋友共进午餐，说她身体不太好。
We always desire to live in peace with our neighbors.我们一贯希望邻里之间友好相处。
To master science means to master laws of nature.掌握科学意味着掌握自然法则。
I have never sought to hide my view.我从未想隐瞒自己的观点。
I do not wish to be disturbed in my work.我不希望有人打搅我的工作。
I intended to come your house last night but it rained.昨天晚上我本想去你家。但下起了雨。
subj. + vt. + for sb. to do sth.:
I shouldn't care for that man to be my doctor.我不应该介意让那人当我的医生。
Can you arrange for the instruments to be delivered on Monday?你安排好星期一将仪器送去吗？
【注释】
help跟不定式作宾语时，可带to,也可不带to。如：
We note with satisfaction that all these activities have helped to promote mutual understanding and friendship between our two countries.我们满意地注意到所有这些活动已有助于促进我们两国间的相互理解和友谊。
By helping them we are helping to save ourselves.通过帮助他们，我们在帮助拯救我们自己。
All this has helped raise farm yield steadily.所有这一切都已促进稳步提高农业产量。
动词不定式作宾语的句型，一般不能转换成被动语态。如：
I like to get up early.不能变为：
*To get up early is liked by me.
但是不定式短语在 decide, desire, hope, intend, plan, propose, suggest 等少数动词的后边作宾语时，可以转换为被动态，这时需要用先行词it作形式主语, 动词不定式短语作真正主语。如：
a
We have decided to enroll more students this year.
It has been decided to enroll more students this year.
已决定今年录取更多学生。
b
They proposed to hold another round of talks in London.
It was proposed to hold another round of talks in London.
已建议在伦敦举行另一轮会谈。
c
We plan to put up 300,000 square meters of dwellings in the city this year.
It is planned to put up 300,000 square meters of dwellings in the city this year.
计划今年在市内建立300 000平方米的住宅。
在need, want, require, deserve等动词后边表示被动意义时，动名词作宾语用主动形式，不定式用被动形式。如：
The house needs painting /to be painted both inside and outside.这房子里外都需要粉刷。
The furniture won*t need polishing tomorrow.明天家具不需要擦了。
The job wants to be done with great care.这项工作需要特别小心地去做。
He certainly deserves to be sent to prison.他的确应该被监禁。
expect, hope, intend, mean, plan, suppose, think, want 等动词的过去完成式与不定式连用时，表示过去未曾实现的希望、打算或意图（参见7.2.1024）。如：
I had intended to write to you.我本打算给你写信的。（实际上未写）
I had wanted to read that book.我本想读那本书的。
We had meant to finish the work in a week.我本想在一个星期内完成这工作。
以it作形式宾语，动词不定式（短语）作真正宾语
动词不定式（短语）作宾语时，如果宾语后边带有宾语补足语，这时就要用社作 形式宾语，将作真正宾语的不定式（短语）移到宾语补足语之后。常用記作形式宾语的 动词有 acknowledge, believe, consider, count, declare, deny, fancy, feel, find, guess, imagine, judge, know, make, prove, realize, report, see, show, suppose, take（ = think）, think, understand 等。另外还有"动词+ 介词"构成的成语 leave...to, owe...to, take...in turn, take...upon oneself等。其句型有以下两种：
subj. +vt.+ it +宾语补足语+ to do sth.（真正宾语）:
They found it impossible to get everything ready in time.他们发现要及时做好一切准备是不可能的。
The new method makes it possible to finish the work in three days.新方法使得有可能在3天内完成工作。
We consider it our duty to do so.我们认为这样做是我们的责任。
I have made it a rule of my life never to regret and never to look back.我已把永不后悔，永不向后看定为我的生活准则。
I regard it as important to finish this job on time.我认为按时完成这项工作是很重要的。
They took it in turn to keep the night watch.他们轮流守夜。
How can you take it upon yourself to say so?你怎么竟然能这么说呢？
I owe it to Mary to explain that she did that on my account.我应该替玛丽解释她是为了我而那样做的。
I must leave it to your own judgment to decide whether you should offer your resignation.我必须让你自己判断，来决定是否该递辞呈。
subj. + vt. + it + 宾语补足语 + for sb. to do sth.（真正主语）：
They thought it desirable for English to be taught in all schools.他们认为在所有学校开设英语课是有好处的。
TV makes it possible for us to see a distance scene.电视能使我们看到远方的景色。
I think it better for you to do the work another way.我认为你最好用另一种方法做这工作。
动词不定式（短语）作介词的宾语
英语中只有少数几个表示“除…之外"意义的介词如besides, but, except, save, than和表示最近将来时的介词about可以跟不定式（短语）作宾语。如：
The enemy had no choice but to lay down their arms.敌人只能缴械投降。
He thinks nothing except to be a doctor.他一心想当医生。
The students taught the peasants besides help /helping them （to） gather in the wheat.除了帮助农民收割小麦，学生们还教他们文化。
There is no cure for birth and death, save to enjoy the intervals.〈谚〉尽情享受人生，因为生死不由人。
What had she done for her father save leave him at the first opportunity?除了一有机会就离开她父亲之外，她为她父亲做过什么？
They thought there was no way out than climb the cliff.他们认为只能爬悬崖出去。
The meeting is about to begin.会议马上开始。
【注释】
①动词不定式作介词but, except, save的宾语时，如果主语部分带有实义动词do, 不定式可以带to,也可以省略to。
②介词besides, save和than虽然可以后跟不定式（短语）作宾语，但用的很少，是比较文气陈旧的用法。besides和than后的不定式可带to,也可省略to。besides 后多跟名词或动名词。
“疑问代词/疑问副词/连接词+不定式（短语）”结构作宾语
本结构作宾语时，可直接位于及物动词之后，也可位于介词之后。其句型是：
subj. + vt. + how /what /when /where /which /who /why /whether + 动词不定式（短语）
To know how to wait is the great secret of success.〈谚〉成功的重要秘诀是懂得如何去等待。
He knows enough who knows how to mind his own business.〈谚〉会料理自 己事务者须具有足够的知识。
I hope youUl advise me what to do.希望你能告诉我该做什么。
No one could tell me where to get the book.没有人能告诉我哪儿可以找到这本书。
Will you advise me which of them to buy?请你告诉我买哪一个好吗？
I don't know who to ask advice from.我不知道向谁请教。
We can't decide whom to invite.我们决定不了邀请谁。
Tell me whether to trust him or not.告诉我是否可以相信他。
“there to be + n. /pron. ” 结构作宾语
本结构作宾语时，可以直接作及物动词的宾语，也可以作介词fbr的宾语。如：
I expect there to be no argument about this.我预料对此事不会有争议。
Would you like there to be a meeting to discuss the question?你想召开一次会议讨论这个问题吗？
She was waiting for there to be another interview.她在等待再次接见。
【注释】
动词是let时，there to be省略to,用there be形式。如：
Let there be no mistake about the program.这个程序不要弄错。
Let there be an end of this misunderstanding.让这种误会终结吧。
4. 动词不定式（短语）作定语
动词不定式短语作定语时，一律位于所修饰的词之后，其中心词多为抽象名词，如 ability （能力），means （手段），order （命令）,thing （事情），way （方法），work （工作） 等。如果不定式所修饰的名词是具体名词，译成中文时常在动词不定式前加“要，需要”, 一般表示的动作在“某个时间”前尚未实现。如：
We have nothing to fear but fear itself.〈谚〉人最怕的是害怕本身。
There's no need to let such a trifle prey on your mind.你无须为这区区小事而烦恼。
A good teacher must have the ability to put himself in the learner's place. 一个好老师必须能设身处地为学生着想。
不定式作定语时，与其修饰的中心词之间有各种不同的关系，现将常见的几种情况详述如下。
1. 中心词是由动词派生出来的抽象名词，原动词可用不定式作宾语。在这种结构中，名词中心词与修饰它的不定式有同位关系，即不定式对其所修饰的名词（词组）的内容起一种解释作用。常见的这类名词中心词如arrangement, attempt, claim, decision, desire, determination, failure, hope, intention, need, order, plan, promise, refusal,resolution, tendency, threat, wish 等。
They made a decision to put off the meeting until next week ( = They decided to put off...).他们决定将会议推迟到下星期。
His refusal to come to our English evening was most disappointing ( = That he refused to come...).他拒绝参加我们的英语晚会，这使人非常失望。
The principal announced his intention to retire ( = He said that he intended to retire). 校长宣布他打算退休。
2. 中心词是由形容词派生出来的抽象名词，原形容词后边常常可以用不定式作原因状语, 或同不定式连用构成复合谓语。常见的这类名词中心词如ability, ambition, anxiety, curiosity, eagerness, impatience, patience, reluctance, willingness 等
He was filled with ambition to become an engineer.他渴望成为一名工程师。(=He was ambitious to become..,不定式作原因状语)
She was burning with curiosity to know the end of the story.她很想知道故事的结局。 (=She was curious to know...不定式作原因状语)
Smith's unwillingness to take the post was difficult to understand.史密斯竟然不乐意接受这一职位真是令人难以理解。(=That Smith is unwilling to take the post was difficult to understand, be unwilling to do sth.复合谓语)
3. 动词不定式与它所修饰的名词中心词之间有同位关系，说明被修饰名词的内容。常见的这类名词中心词如 campaign, chance, courage, efforts, evidence, means, measures, method, move, movement, opportunity, position, power, project, reason, right, skill, strength, struggle, way 等
The committee began a campaign to raise production and practice economy.委员会发起一项提高生产，厉行节约的运动。
Their efforts to improve the working conditions have succeeded.他们要改善工作条件的努力获得成功。
There wasn't enough evidence to prove him guilty of the crime.没有充足的证据来证明他犯了罪。
The general manager has announced new measures to deal with inflation.总经理宣布了对付通货膨胀的新措施
4. 中心词与作定语的不定式之间有逻辑上的主谓关系，即中心词是作定语的不定式动作的执行者，是不定式的逻辑主语。不定式作这种后置定语时，相当于关系代词作主语 的定语从句。其中心词可以是名词、代词或数词
（1）中心词是名词：
We are in need of nurses to take care of children.我们需要护理儿童的护士。(=... nurses who can take care of...)
China was the first country to use gun powder. 中国是第一个使用火药的国家。 (=...country that used...)
This is the sixth case of influenza to occur ( = that has occurred) in the town this time. 这是这次城里发生的第6个流感病例。
（2）中心词是代词：
Is there anybody to carry on the work?有人去做这项工作吗？
There was much to interest and amuse him.有许多使他感到有趣好笑的东西。
There was no one to look after the child.没有人照看这孩子。
We also had quite a number of visitors, some to see us off, some to fetch things, and some to do both.我们也有不少来客，有送行的，有拿东西的，有送行并拿东西的。
He has written two articles for the journal, one to be published in this issue, the other to come out in the next.他为这个杂志写了两篇文章，一篇在本期发表，另一篇在下期刊载。
(3)中心词是数词：
He is always the first to come and the last to leave.他总是第一个来到，最后一个离开。
The second to do the experiment is Mary.第二个做实验的人是玛丽。
5. 中心词和作定语的不定式之间有逻辑上的动宾关系，即中心词是作定语的不定式的动 作接受者，是不定式的逻辑宾语。这种不定式作定语，相当于关系代词作宾语的定语从句。所以作定语的不定式后边不能带宾语。在这种句型中，作定语的不定式经常是 主动形式表被动意义。其中心词可以是名词、代词或数词。常用的句型有4种
（1）"There + be + subj. inf. phr.”句型:
There are many difficulties to overcome.有许多困难需要克服。
There was no experience to fall back on.没有任何可供借鉴的经验。
We leave more to do when we die, than we have done. 〈谚〉人死方知事未休。
Isn,t there anything for me to do?有什么事可让我做吗？
There isn't much to see here.这里没有多少东西值得看。
There is always something to be cut off young trees if they are to grow well.〈谚〉好花不浇不盛开，小树不修不成材。
There's really nothing to be said.确实没有什么可说。
【注释】
在There be句型中，动词不定式作定语，被修饰的中心词是不定式的逻辑宾语时, 用主动式与被动式均可，意义没多大区别，所以一般情况下多用主动形式表被动意义。如：
There are many mistakes to correct /be corrected.有许多错误需要纠正。
但是当由讲话人去执行不定式的动作，表示义务、责任或必要性时，多用主动形式; 由别人去执行动作，表示可能性时，多用被动形式。如：
a
There is no time to lose.我们没有时间可浪费了。( = for us to lose)
There is no time to be lost.没有时间可浪费了。(谁 lose time 不明确)
b
There are still many things to take care of.还有许多事需要我们照料。(=for us to take care of)
There are still many things to be taken care of.还有许多事需要照料。(不一定讲话人亲自去take care of)
应注意的是，有时两种形式意义不同，试比较下列句子：
a
There is nothing to do now. ( = We have nothing to do now.)现在没有事可干。
There is nothing to be done now — we'll have to buy another one. ( = We can do nothing now.)现在没有法办了，我们只得另买一个。
b
There is nothing to see. ( = There is nothing worth seeing.)没有什么东西值得看。
There is nothing to be seen. ( = We can see nothing.)什么东西也看不见。
（2）“subj. + have /want + obj. + inf. phr. ”句型
在这种句型中，句中主语也是作定语的动词不定式的逻辑主语，句中的宾语是中心 词，也是不定式的逻辑宾语。这时作定语的不定玉通常是主动形式表被动意义。如：
He has a large family to support.他有一大家人要供养。
I have nothing really to complain about.我的确没有什么可抱怨的。
He asked for a letter to take back.他要一封回信。
I asked her if she had any rooms to let.我问她是否有房间出租。
（3）"subj. +buy /get /give + 间接宾语 + 直接宾语 + inf. phr."句型
在这种句型中，句中间接宾语是作定语的动词不定式的逻辑主语，句中直接宾语是中心词，也是不定式的逻辑宾语。这时作定语的不定式通常是主动形式表被动意义。如：
He'll show you the right path to take.他会指给你要走的正路。
Can you get me something to eat?你能给我找点东西吃吗？
I'll buy you some magazines to read on the journey.我给你买些杂志带着旅途中读。
（4）“subj. +叫 phr, + be + 表语”句型
在本句型中，句中主语是中心词，也是作定语的动词不定式的逻辑宾语。如：
The thing to do now is to carry out an experiment.现在要做的事是做实验。
The best thing to do now is to check the result again.现在要做的首要事情是再检查一遍结果。
The only thing to do now is to take over his job.现在要做的唯一事情是把他的工作接过来。
【注释】
当不定式作定语，其中心词是不定式的逻辑宾语时，如果不定式是不及物动词，后边需要用介词。要注意这时介词后边不能跟宾语。如：
Can you find us some records to listen to?你能为我们找些唱片听吗？
Is this the only point for us to pay attention to?这是要我们注意的唯一问题吗？
She has a large family to take care of.她有一大家人需要照顾。
They mailed me a couple of forms for me to fill in.他们寄给我几张表要我填。
6. 如果中心词是作定语的不定式动作的地点、方式、工具等，不定式后边一般要用介词来表示这种关系。这种带介词的不定式作定语可以转换成“介词+关系代词+ to + y.”结构作定语（参见17.4.5）
He is looking for a room to live in （ = He is looking for a room in which to live）.他正 在找个房间住。
I have no pencil to write with （ = I have no pencil with which to write ）.我没有铅笔写字。
There is a tree over there to sit under.那边有棵树可以坐在下边。
I want a strong box to put all these books in.我要一个结实的箱子把所有这些书放进去。
That's the only way （in which） to overcome the difficulties.这是战胜这些困难的唯—方法。
7. 被only, the first, the second, the last, the next或其他序数词和最高级形容词修饰的名词，常用不定式作定语
I don't think he is the best man to do the job.我想他不是做这工作的最佳人选。
They are the first to bear hardships, the last to enjoy comforts.他们是吃苦在先，享受在后的人。
I arrived first. The next one to arrive was James.我第一个到达。接着来的一个是詹姆斯。
The only way on earth to multiply happiness is to divide it.〈谚〉世间唯一成倍增加幸福的办法是与人分享。
He is the second man to be killed in this way.他是以这种方式被杀害的第二个人。
8. whether to do结构作定语
The question on radiation cancer whether to be or not has been decided now.是否是射线癌这个问题现在已确定了。
9. 动词不定式（短语）作隔离后置定语
（1） 被其他后置定语隔离
动词不定式作后置定语时，一般直接位于其中心词之后，但是如果中心词除了不定 式作定语外，还有其他后置定语，如形容词、介词短语、定语从句等，这时作定语的不定式往往位于其他后置定语之后，从而与其中心词形成隔离。如：
I have got something very important to say.我有很重要的事要说。
Have you got anything interesting to tell us?你有什么有趣的事告诉我们吗？
He thought of the battle that lay ahead to capture the city.他想到将要到来的攻占城市的战斗。
但是如果其他定语较长，而不定式较短，间或不定式可放在其他定语前边。如：
I give him a book to read on the development of modern English.我给他一本关于现代英语发展的书让他读。
（2） 被谓语隔离
如果中心词是主语，中心词与作后置定语不定式有时被谓语隔开。这往往是由于谓语短，而作后置定语的不定式较长。如果不将谓语提前，会使句子头重脚轻。如：
The day has come to settle accounts with the cruel landlord.和凶恶的老板算账的日子来到了。
At the meeting a decision was made to transfer a part of the students to another school.在会议上做出一项决定要把一部分学生转到另一所学校。
（3） (3)被状语隔离
如果中心词是宾语，有时它和作后置定语的不定式被修饰谓语的状语分开。如：
He received orders this morning to pull out of the city at once.他今天早晨接到立即撤到城外的命令。
5. 动词不定式(短语)作状语
动词不定式具有副词的特征，常被用作状语，在句中表目的、原因、结果、程度、条件等。
1. 动词不定式(短语)作目的状语
不定式作目的状语位于句首比在后边更为正式，语气更重些。常用的句型有5种。
（1） 直接用不定式(短语)作目的状语：
To learn a language well, you must make painstaking efforts.要学好一种语言，必须下苦功夫。
Different measures have been taken to prevent pollution.为了 防止污染，釆取了 各种不同措施。
Sell not virtue to purchase wealth, nor liberty to purchase power.(谚〉勿以美德换财富，勿以自由换权力。
I come here, not to rake up old differences, but to let bygones be bygones.我到这里来，不是为重提过去的那些旧分歧，而是忘掉旧嫌，恢复和好
【注释】
在美国英语中，在动词come, go, run后作目的状语的不定式可以省略to。如：
I'll go tell him about it.我去告诉他此事。
Come watch TV with us this evening.今晚来和我们一起看电视。
Run help that old woman over there.快跑去帮助那边的那位老太太。
（2） in order to +v.作目的状语
本句型中，in order to引导的不定式短语可位于句首，也可位于句中。如：
In order to accomplish the task well, we must understand to the last detail how the matter stands.为了把任务完成好，我们必须对情况了如指掌。
He was saving as much as possible in order to repay Jennie eventually.他在尽量多积些钱以便最终还清欠珍妮的款。
（3） so as to +v.作目的状语
本句型中，so as to引导的不定式短语不能位于句首，只能位于句子的后半部分。如:
He served as a librarian so as to have plenty of books to read.他当图书管理员为的是有很多书看。
They worked hard so as to end the task with success.他们努力工作以便圆满完成任务。
We hurried so as not to be late.我们急忙赶路以免迟到。
（4） “so + v. + as to + v."结构表目的:
A man must so train his habits as to rely upon his own courage in moments of emergency. 一个人必须养成这样的习惯，以便在紧急关头依赖自己的勇气。
Please so arrange the exhibits as to give the central theme special prominence.请将展品为样摆放，以便特别突出其中心主题。
有时用“so + adv.+as to +v.”结构表示目的。但是在这种句型中，要注意句中的时态要用将来时，而不能用过去时。如：
We shall work so hard as to overcome our difficulties.为了克服困难，我们将会非常努力地工作。
（5） for there to be结构作目的状语：
For there to be no mistake, you must recheck the results got from the experiment.为了不出错误，你必须重新检查实验结果。
For there to be life, there must be air and water.要有生命，必须有空气和水。
2. 动词不定式（短语）作原因状语
动词不定式作原因状语主要有两种句型：一是位于表示感情的不及物动词之后，说明动词发出动作的原因；一是位于作表语的形容词和过去分词之后，说明形容词和过去分词。
（1） 位于表示感情的不及物动词之后，说明其前边动词动作的原因。如：
She trembled to think of it. 一想到此事她就不寒而栗。
The old woman wept for joy to hear that her son returned safe and sound.听到儿子平安无事地归来，老太太高兴地哭起来。
He walked slowly as though his legs ached to move.他走得很慢，似乎一动腿就痛。
（2） 位于作表语的形容词和过去分词之后。
不定式位于形容词和过去分词之后作原因状语有5种不同情况：
①作表语的形容词和过去分词表示句中主语的情绪或感情。常用的这类词有：
形容词 afraid, angry, anxious, content, eager, furious, glad, happy, hesitant, impatient, indignant, jubilant ，mad, proud, sorry, thankful wild 等。
过去分词 amazed, ashamed, astonished, bored, delighted, disappointed, displeased, dissatisfied, excited, gratified ，horrified, overjoyed, pleased, shocked, surprised, thrilled 等。
例句
He was very angry to hear that she had broken her word.听说她失信他非常气愤。
I'm very sorry to give you so much trouble /to keep you waiting /to hear that you've been ill /to learn that you can't come.实在对不起给你这么多麻烦/让你久等。/ 听说你病了 /闻悉你不能来我很难过。
He will be happy to accept your kind invitation.他很高兴接受您的善意邀请。
He was thrilled to learn that he had won a prize.获悉他得了奖他一阵激动。
He was disappointed to find that all the tickets were sold out.发现票已全部售完他很失望。
I'm quite ashamed to have to trouble you.十分不好意思不得不麻烦你。
在这种句型中，不定式的逻辑主语往往是句子的主语。如果不定式有自己的主语, 即句子的主语不是不定式的逻辑主语，就要用for...to结构。如：
They were impatient for the bus to start.他们急不可待要汽车开动。
Everybody is anxious for you to accept the position.大家都渴望你能接受这个职位。
②作表语的形容词表示说话人对主语做某一动作的评价，这一动作由不定式表示出来。这种句型的主要特点是：
•动词往往是be,虽然也可以用appear, seem等。
•主语总是有生命的东西。
•这种句型可以改写成其他两种句型：
subj. + be + adj. + inf. phr.
=It + be + adj. + of + 原主语 + inf. phr.
=How + adj. + of + 原主语 + inf. phr.
例句
a
You were careless to leave your bike unlocked.
=It was careless of you to leave your bike unlocked.
= How careless of you to leave your bike unlocked.
放下自行车不锁，你真粗心。
b
You are very kind to come and see me.
=It's kind of you to come and see me.
= How kind of you to come and see me.
谢谢你来看我。
c
He was foolish to agree to the proposal.
=It was foolish of him to agree to the proposal.
= How foolish of him (it was) to agree to the proposal.
=How foolish (it was) of him to agree to the proposal.
他真愚蠢竟然同意那建议。
用于本句型的形容词即可以用来表示说明人的品质，也可以用来表示说明人的行 为和人做的事(something that he does)。我们可以说:a kind person, a brave person, a foolish person,也可以说:a kind act, a brave deed, a foolish action。其他例句如：
The boy was rude to speak to the teacher like that.该男生那样对老师讲话太没礼貌。
You are thoughtful to do all this for the old professor.能为老教授做这一切你考虑得很周全。
You were right to give up smoking.你戒烟做得对。
在这一用法中，偶尔句子的表语不是表示说明人的品质的形容词，而是一个说明具有某种品质的人的名词。如：
He is a coward to escape his duty.他逃避责任，是个懦夫。
He is a clever boy to have led the enemy into the valley.他把敌人引进了山谷，真是个聪明的孩子。
在口语中用感叹句或以it为形式主语的of句型更为普遍，如：
How considerate it was of her not to worry you when you had so many things to do.她很体贴人，当你有很多事情要做时，她不去打扰你。
How brave of him to go into the burning building to save the old man.他真勇敢跑进燃烧的楼里去救出那位老人。
It was crazy of you to go skating on such thin ice.你真是疯了，在这么薄的冰上滑冰。
③作表语的形容词表示不定式动作的性质，表示说话人对不定式动作的看法或感受。在这种句型中，不定式为不及物动词时，后面要带介词。句中的主语是不定式的 逻辑宾语。本句型可以改写成其他3种句型，即：
subj. + be + adj. + inf. phr.
=inf. phr. + 原主语 + be + adj.
=It + be + adj. + inf. phr. + 原主语
=How + adj. + it + be + inf. phr. + 原主语
概要
a
This room is pleasant to work in.
= To work in this room is pleasant.
=It's pleasant to work in this room.
=Isn't it pleasant to work in this room?
= How pleasant it is to work in this room.
= How pleasant to work in this room.
在这个房间里工作真舒适。
b
Oil is not easy to find or to get out of the earth.
= To find or get oil out of the earth is not easy.
=It's not easy to find or get oil out of the earth.
找到并从地下打出石油不容易。
本句型中常用的形容有 comfortable, dangerous, difficult, easy, exciting, expensive, fascinating, hard, impossible, interesting, painful, pleasant, safe, simple, thrilling 等。如:
Some people are hard to please.有些人难以使其满足。
This new equipment is expensive to install.这种新设备安装起来很昂贵。
Machines can perform many tasks which are impossible to do by hand.机器能做很多手工不能做的工作。
上述形容词可以作表语，也可以作定语。因此，这种句型也可以改写成由形容词作前置定语，不定式作后置定语的句子。如：
a
She's pleasant to work with.
= She's a pleasant girl to work with.
和她一起工作是很快活的。
b
This question is hard to answer.
=This is a hard question to answer.
这是一个难以回答的问题。
如果主语所表示的是不定式动作的地点、方式、工具等，要在不定式后加介词来表示这种关系。如：
This river is dangerous to bathe in.在这条河里洗澡有危险。
She has always been easy to get along with.她总是很容易与人相处。
This armchair is not comfortable to sit in.这把扶手椅坐起来不舒服。
The story of his adventures was exciting /fascinating /interesting /thrilling to listen to. 他冒险的故事听起来令人激动/很吸引人/很有趣/很动人。
④作表语的形容词表示主语的特点，作状语的不定式对它加以说明。如：
The coffee is ready to drink.这种咖啡即冲即饮。
The boys were quick to react to the teacher's questions.这些孩子们对老师的提问反应敏捷。
The man was slow to understand what I said.那人对我的话理解很慢。
They are prompt to do whatever they are assigned to.他们能迅速完成分配的各项工作。
⑤for there to be + n.结构作原因状语，如：
I'm anxious for there to be plenty of discussion.我担心会有许多议论。
（3） 动词不定式（短语）作原因状语的说明
①英语中有些形容词如 able, afraid, anxious, apt, bound, certain, easy, fit, likely, ready, sure等，本身意义不完整。这类形容词作表语时，后边常跟一个不定式使其 意义完整起来。这时的不定式不是作原因状语，而是同前边的形容词一起构成复合 谓语。不定式前边的系表结构叫做半助动词（详见7.5.2.1半助动词）。如：
He is able to live on his salary.他能靠工资维持生活。
You are certain to be happy with them.和他们在一起你肯定快乐。
He knew that no patient was likely to ring him at that hour.他知道在那种时刻病人不会给他打电话。
上述形容词后的不定式如果表示被动意义，通常都要用不定式的被动式，不用主动式表被动意义。如：
Such a mistake is apt to be made in your written work.写作时，很容易犯这样的错误。
We are liable to be overheard here.在这里我们容易被别人偷听。
The book is not likely to be published this year.这本书今年不可能出版。
但是ready和fit后的不定式用主动式或被动式都可以，如：
This plant is fit to eat /be eaten.这种植物可食用。
The cake is ready to eat /be eaten.蛋糕已做好，可以吃了。
②有些“adj.+不定式（短语）”结构中，不定式含有被动意义，与句中主语构成动宾关系，但是不定式要用主动式，不用被动式。这种句中的形容词本身必须意义 完整，其后的不定式可以改为“for...to”结构，如：
A lorry in good condition is easy （for the driver） to control.保养良好的卡车容易驾驶。
Smith's unwillingness to take the post was difficult （for us） to understand.史密斯不肯接受这一职位令人难以理解。
Modem farms aren't expensive to develop.经营现代化农场花钱不多。
上述句子都可以改写成以It作形式主语，动词不定式（短语）作真正主语的句型。这时原句中的主语就成了动词不定式的宾语。如：
It is easy (for the driver) to control a lorry in good condition.
It was difficult (for us) to understand Smith's unwillingness to take the post.
It is not expensive to develop modern farms.
不定式(短语)作原因状语时，以主动形式表被动意义主要有以下两种情况：
表示说话人对不定式动作的看法或感受的形容词后的不定式常用主动形式表被动意义。常用的这类形容词有comfortable, dangerous, difficult, easy, exciting, expensive, fascinating, hard, impossible, interesting, painful, pleasant, safe, simple, thrilling 等。如：
The lecture was hard to understand.这个讲座难以听懂。
The story of her suffering was painful to listen to.她所受的苦难听起来让人心酸。
表不句子主语(人或物)所具有的特征的形容词，如beautiful, big, bright, clear, frosty, heavy, rough, smooth, steep, thin, valuable 等。如：
Venus is bright to see without a telescope.金星很亮，不用望远镜也能看得见。
In Tibet the air is thin to breathe.在西藏，呼吸起来空气中的氧气稀薄。
3. 动词不定式(短语)作结果状语
不定式作结果状语时，位于被修饰的动词之后，常用的有以下6种句型。
(1) too...to do something 太…以致不能…
本句型是肯定形式表示否定意义。不定式所修饰的词是不定式的逻辑主语。如果不定式表主动意义，它就是不定式动作的执行者；如果表示被动意义，它就是接受者。如 果不定式动作执行者或接受者不是被其所修饰的词，就要用“for...to”结构，将不定式的 动作执行者或接受者由for后边的词表示出来。如：
We found the room too small to hold so many people.我们发现这房子太小了容纳不了这么多的人。
He was too excited to fall asleep.他激动得睡不着觉。
I've come too late to prevent him from going there.我来得太晚未能阻止他去哪里。
He is too old to work for his bread.他年纪太老，不能赚钱糊口 了。
下列例句中的不定式用主动形式表被动意义：
The problem is too complicated to solve.这个问题太复杂，无法解决。
Ultrasonic waves are too high in frequency to hear.超声波音频太高听不见。
The metal is too hard to machine.这种金属太硬，无法加工。
下列例句中的不定式用被动式表被动意义：
Atoms are too small to be seen by the human eye.原子太小，人的眼睛看不见。
The place was too far away to be reached in two hours5 time.那地方太远，2 小时到 达不了。
The pain was too horrible to be described.那种疼痛太可怕，无法用语言描述。
下列例句中的不定式带有自己的逻辑主语，用“for...to”结构：
The weather is too hot for anyone to eat anything.天气热得让人吃不下饭。
The problem is too unimportant for him to consider.这个问题不重要，他不会考虑。
在使用too...to结构时，要注意下列4种不同的特别意义：
①表否定时，too = more than enough “太,过分”。这时too后边的形容词多是表示性质或特征的，too对其后边的形容词或副词起一种消极作用。这种句型的主语可用人或物。如：
The doctor was too busy to answer the telephone.医生忙得没空接电话。
The air fifty miles up is too thin to carry sound. 50 英里的高空中，空气太稀薄不能 传播声音。
②表肯定时，too = very, extremely, exceedingly “很，非常，实在，简直，太 ”。too 后的形容词往往是表示“乐意，愿意，容易”等意义的词，如apt, eager, easy, glad, happy, liable, pleased, ready, willing 等。这时 too 在句中对形容词起积反作用，其前经常有all, but, only等副词修饰。句中主语多为人。如：
Beginners are too apt to overlook such grammatical errors.初学者很容易忽视这些语法错误。
She is too eager to know the result of the test.她急于想知道考试成绩。
She is too willing to help others.她非常乐意帮助他人。
They are all too satisfied to take the opinions of others without the pain of thought for themselves.他们都太满足于听取别人的意见，自己懒得去想。
Without this computer we are but too liable to make miscalculations.没有这台计算机，我们很容易出计算错误。
We are but too glad to meet you.我们很高兴见到你。
Fm only too happy to be of service.我能帮点忙真是求之不得。
You are only too ready to find fault with others.你太好找别人的毛病了。
The students are only too pleased to speak English with the foreigners.学生们很喜欢 与外国人讲英语。
③”not/never too...to”表肯定，意义为“并不太…所以能；不太…可以…”。如：
He is not too old to do the work.他并不太老，可以做这工作。
One is never too old to learn.活到老，学到老。
④“too...not to”意义为“太…不能不…”，表双重否定。如：
He is far too wise a man not to see that.他是个很聪明的人，不会不懂得那一点。
He was too angry not to say that.在盛怒之下，他难免说出这种话来。
This was too great an honour not to excite the envy of his rivals.这是一个非常大的荣誉，不会不引起其竞争者的妒忌。
⑵“ (only) to +不定式(短语)”往往表示意想不到或是不愉快的结果。如：
She left home only to find life more difficult.她离家出走，结果发现生活更困难。
I rushed to the station as fast as I could, only to find the train had already gone.我尽快赶往车站，却发现火车已开走了。
（3）so...as to do意义为“如此…以致…”，表结果【本句型中的谓语动词通常用过去 时】。如：
She sang so well as to bring down the house.她精彩的演唱博得满堂喝彩声。
His criticism was so sharp as to set quite a few comrades on pins and needles.他的批评非常尖锐，使许多同志如坐针毡。
She was so excited as to be unable to say a word.她激动得一句话也说不出来。
这种句型经常用来提岀请求，这时句中谓语动词通常用现在时或将来时，疑问句常用will或would来引导。如：
Would you be so kind as to pass me the dictionary?请把字典递给我好吗？
Be so kind as to help me in doing the sum.劳驾，请帮我算一下。
（4）be such as to do意义为“如此…以致…”，表结果。如：
The job is such as to demand the greatest skill.这种工作非同小可，它要求最高超的技术。
The working conditions are not such as to cause the machine to be out of order.操作条件不至于使机器发生故障。
His illness was not such as to cause anxiety.他的病不足以令人焦虑不安。
（5）such + n. + as to do something意义为“如反…以致…”，表结果。如：
This is not such weather as to encourage out-door sports.这不是鼓励户外运动的那 种天气。
The book was written in such an interesting way as to be enjoyable to young and old alike.这本书写得如此有趣，凡是读者，不分老少，都很欢迎。
He is not such a fool as not to be able to see that.他不至于傻到连那都不明白。
（6）so as to do "到…程度以致…":
The day was dark, so as to make a good photograph hard to get.天色阴暗，因此照片效果欠佳。
He shouted so as to be heard a mile away.他高声叫喊，1英里之外都听得见。
（7）too...for there to be + n.有时可以用来表结果：
It's too late for there to be any buses.天太晚，不会有公共汽车了。
4. 动词不定式(短语)作程度状语——enough to do something足以
He is man enough to admit his mistake.他勇于承认自己的错误。
Is this table large enough for six men to sit round?这张桌子可以坐下 6 个人吗？
This bed is large enough for two people to sleep in.这张床很大，足以睡下两个人。
注意not enough to的意义:
The patient wasn't sick enough to go to the hospital.这个病人并没有病到要去住院 的程度。
He's not fool enough to believe that.他不至于愚蠢到会相信那事。
I'm not scholar enough to name this plant.我才疏学浅，讲不出这种植物的名字。
I don't know him well enough to ask him for help.我和他不够熟，不便请他帮忙。
The patient wasn't strong enough to undergo the operation.病人的身体还不够壮，经受不住手术
【注释】
too... to结构有时改用反义形容词后，可以与not enough to结构转换使用。如：
a
He was too impatient to work in the laboratory.
He wasn't patient enough to work in the laboratory.
他太没有耐心，不能在实验室里工作。
b
The boy is too short to reach the upper shelf.
The boy is not tall enough to reach the upper shelf.
这孩子长得不高，够不着上层的架子。
c
The road is too narrow for two cars to pass.
The road is not wide enough for two cars to pass.
这条路太窄，两辆汽车跑不开。
5. 动词不定式(短语)作条件状语
动词不定式短语有时用作条件状语。在这种句型中，句中的谓语动词常与will, would, shall, should, can, could, must等情态动词连用，句子的主语通常也是作条件 状语的动词不定式的逻辑主语。作条件状语的不定式短语可位于句首，也可位于句末，但 不定式的否定结构则多置于句末。位于句首时，不定式短语后要用逗号与句子的其他成 分分开。如：
To put their heads together, they will find ways to tide over the difficulties. ( = If they put their heads together, they will find...)只要集思广益，他们定会找出渡过困难的办法。
To hear him talk, you would think he was a millionaire. ( = If you were to hear him talk, you would think...)要是听他讲话，你定会认为他是一位百万富翁。
How can you catch the train to start so late? ( = If you start so late, how can you catch ...?) 如果这么晚才动身，你怎么能赶得上火车？
One would get into trouble to do such a thing. ( = If you should do such a thing, you would get into...)如果干这种事，就会惹麻烦。
You would be in much trouble not to follow the rules. ( = You would be in much trouble if you do not follow the rules.)要是不遵守这些规章制度，你会陷入麻烦之中。
有时for...to do sth.结构表示条件意义。这时，不定式的逻辑主语是for后边的名词或代词。如：
You will regret one day for your son to marry her. (You will regret one day if your son marry her.)要是你儿子与她结婚，总寿一天你会后悔的。
6. 动词不定式（短语）作让步状语【在这一结构中，句中谓语动词通常是否定形式】
To go to the world's end, you could not find another like it.即使走遍天涯，你也找不 到另一个和它一样的东西。
I will never do that, to save my life.即使为救我的命，我也决不会干那种事。
To live a thousand years, one may not learn enough.即使活上千年，一个人也学不 到家。（活到老，学到老。）
6. 动词不定式（短语）作宾语补足语
动词不定式作宾语补足语时，宾语是不定式的逻辑主语。常用的句型有以下3种。
1. 动词不定式（短语）作宾语补足语时，可变为被动语态的5种句型（注意事项请参见 7.3.3.2和7.7.1.7中的注释）
（1） 用于表示命令、教导、要求、允许、意向、起因、使、禁止、劝告、警告等意义的动词之后。常用的这类动词有advise , allow , ask, beg , beseech , bribe ，cause , challenge , command , compel , dare ，direct , drive （= compel）, empower ，enable , encourage , entitle ，entreat ，expect , forbid , force , get , give , impel ，implore，incite，induce ，instruct, intend， invite, know, lead , mean （= intend）， oblige，order , permit , persuade, predispose ，press （迫使），remind , request , require , teach , tell , tempt , urge （= press）, warn 等。如:
He gave me to understand that he could help me.他使我明白他能帮助我。（give 在这里是使动词）
The doctor warned the patient not to smoke.医生警告病人不要吸烟。
Did he mean /intend us to share the cost of the dinner?他是不是有意要我们分摊晚餐费？
（2） 用于表示意见、判断、信念、料想、声明、认可或心理感觉等意义的词。本句型是比较正式文体，多用于书面语。作宾语补足语的不定式to be常常被省略，但是它的完成式to have been不能省略。常用于本句型的动词有acknowledge , announce , appoint , assure，believe , choose， claim，consider , declare , elect , feel , find , guess，hold , imagine， judge， know , name , proclaim , prove， realize , report , suppose , take , think，understand 等。如：
We supposed them to have trial-produced new products.我们猜测他们己经试制出新产品。
They all acknowledged Harry to be the cleverest boy in the class.他们都承认哈里是班里最聪明的学生。
We took your silence to mean that you agreed.我们认为你的沉默就意味着你同意了。
（3） 用于表示生理感觉的动词 behold , feel , hear , look at , listen to , mark，notice , observe , perceive , see , watch等之后。这些动词后跟不定式作宾语补足语时，不定式 前省去too如：
Did you notice anyone leave the room?你注意到有人离开房间吗？
We observed tears come into her eyes.我们看到她满眼含泪。
I didn't perceive anyone come.我没有看见有人来。
It's quite interesting to look at other people play chess.看别人下棋很有趣。
（4） 用于表示“致使，让”等意义的动词bid , have , let , make等之后。这些动词后跟不定式作宾语补足语时，不定式前省去to。如：
Do not let the mind dwell upon what you cannot obtain.〈谚〉不要异想天开。
We must not let the matter rest here.我们一定不能让这事就此罢休。
Bid him come here as soon as possible.叫他尽快来这里。
We shall have you know the results when the experiment is over.实验一结束我们就将结果告诉你。
【注释】
drop , escape , fall , fly , go , slip 在let的宾语后作宾语补足语时，经常把宾语放在 drop , fall , fly , go , slip后边，形成倒装语序，特别是当宾语有短语修饰时：
Don't let escape the opportunity of the present, it will not return.〈谚〉机不可失， 时不再来。
When prosperity was well mounted, she let go the bridle, and soon came tumbling out of the saddle.（谚〉成功时，莫放松，否则成功会落空。
He let fall a hint about his intentions.他无意中透漏了他的意图。
Don't let slip any opportunity of practicing your English.别错过任何练习英语的机会。
She let fly a torrent of abuse at him.她对他一阵连珠炮似的谩骂。
（5） 用于表示表示经历、经验的词know之后。know表示此义时，后跟作宾语补足语的 不定式前省去to。本句型中的know是以完成式（有时是过去式）出现的，其他时态不适用于本句型。其意义为“看过，听过，有过（某种）经验或知识二主要讲一个人的态度和行为，具有“经验”意义。如：
Have you ever known her lose her temper?你曾经看见过她发脾气吗？
Never have I known him speak English so fluently.我从来不知道他讲英语这么流利。
I have never known bacteria benefit the mankind.我从来不知道细菌会有益于人类。
2. 动词T定式（短语）作宾语补足语时，不能变为被动语态的句型
表示喜爱、厌恶、偏爱的词，如 bear , get , hate , help , leave , like , prefer , want , wish 等后跟有不定式（短语）作宾语补足语时，该句通常不能变成被动句。如：
He likes his wife to dress well.他喜欢自己的妻子打扮得漂亮。
不能说：*His wife is liked to dress well.
其他例句如：
She can't bear me to be unhappy.我不开心她受不了。
Do you wish me to do the experiment with you?你想要我和你一起做这个实验吗？
Her parents left her to choose her own friends.她父母让她自己选择朋友。
The committee would prefer the matter to be discussed at the next meeting.委员会宁愿将这个问题在下次会议上讨论。
【注释】
help后的不定式作宾语补足语时，可带to,也可不带，主要看主语参与动作的情况。 当主语参与作宾语补足语的不定式的动作时，多不带to；当主语不参与不定式的动 作时，多带to。美国英语通常不带to。如：
Will you help me clear the table?你帮我把桌子收拾干净好吗？（主语参与clear 的作）
He helped the family conceal the disgrace.他帮着家人隐瞒不光彩之事。（主语参与conceal的动作）
I thought seeing him would help her to get better.我想见到他会有助于她的病情好转。（主语为动名词短语“seeing him”,未参与get的动作）
This book helped me to see the truth.这本书帮助我看清事实真相。（主语未参与see的动作）
3. 成语动词后跟不定式作宾语补足语
常用的这类成语动词有 care for , call on , count on , depend on , long for , rely on , vote for 等。如：
We can not count on another country to help us.我们不能指望另一个国家来帮助我们。
We voted for the meeting to be cancelled.我们投票赞成取消这次会议。
The President called on his people to make sacrifices for the good of their country.总统号召国民为了国家的利益做出牺牲。
7. 动词不定式（短语）作主语补足语
动词不定式作主语补足语时，句子的主语也是不定式的逻辑主语：
Mathematics is known to be the base of all other sciences.数学被认为是所有其他学科的基础。
He is thought to be the best player of basketball.他被认为是最佳篮球运动员。
The difference between one element and the other was proved to be in the structure of their atoms.已证明元素之间的区别在于其原子的结构不同。
【注释】
①本句型中的动词变成被动语态时，作主语补足语的不定式前一律带to，但在let drop , let fall , let fly , let go , let slip 中，不带 to:
A few hints were let fall by the girl.有些线索被这女孩无意中说了出来。
When they are let go to fly again, homing pigeons find their way home.当再次放飞后，信鸽能飞回家。
The war criminals were let go.战犯全被释放了。
The opportunity was let slip.机会错过了。
②有少数充个动有，如calculate , repute , say等只能用在被动态句中，主动句中不能用不定式作宾语补足语。如：
The hall was calculated to hold about a thousand people.该大厅估计可容纳1000 人左右。
He was reputed to be a good writer.他是公认的优秀作家。
He is said to have done six copies.据说他已写了6 本书。
8. 动词不定式（短语）作插入语
动词不定式作插入语多为一些固定短语，如so as to say , so to speak , strange to say , to be brief , to be exact , to be frank （with you）, to begin with , to be honest , to be just , to be plain , to be sure , to bring the story short , to conclude , to cut the matter short , to make a long story short , to make matters worse , to put it another way , to put it plainly , to put it straight , to return to my subject ，to start with , to sum up , to take a medical view , to tell（you）the truth 等。如：
To tell the truth, I don,t know how to do the work at all.说真话，我根本不知道如何来做这工作。
To be honest, I don't know anything about it.老实讲，对此事我一点不知道。
He is, so to speak, the brains of the organization.可以说他是该组织的智囊。
To be sure, he's rather young for such an important position.当然，对于这么重要的 一个职位来说，他有些年轻。
To be just, he has lots of qualities.公正地说，他有许多好品质。
So as to say, your daughter is the most distinguished among them.可以这么说，您女儿是她们中最杰出的。
To cut the matter short, it doesn't have anything to do with you.简而言之，此事与你没有任何关系。
To take a medical view, all substances are more or less poisonous.从医学的角度看，凡是物质或多或少都是有毒的。
To be frank with you, I like you, and should be glad to give you any help I can.坦率地说，我喜欢你，并且高兴尽力帮助你。
The rush work was completed in less than one day 一 six hours, to be exact.这项紧急工作不到一天就完成了 ——确切地说，6个小时。
To begin with, there must be close co-operation between them.首先，他们之间必须紧密合作。
9. 动有不定式（短语）作同位语
动词不定式可作名词的同位语，说明所修饰的名词的具体内容，一般都用逗号，破折号或分号隔开。如：
We all have a common dream 一 to become a teacher.我们都有一个共同的梦想——成为一名教师。
There is only one success 一 to be able to spend your life in your own way.〈谚〉成功只有一个——能以自己的方式度过人生。
There are three things extremely hard: steel, a diamond and to know one's self.〈谚〉有三种东西最坚硬：钢铁、钻石和自知之明。
He came to Yan’an for the same reason, to support the Chinese people in their national liberation war against Japan.他基于同样的原因来到了延安——支持中国人民抗日民族解放战争。
有时“名词/主格代词+不定式”复合结构起到一种同位语的作用，来解释说明其前面的名词。如：
We also had quite a number of visitors, some to see us off, some to fetch things, and some to do both.我们也有不少来裘，有送行的，有来拿东西的，还有既送行又来拿东西的。
He has written two articles for the journal, one to be published in this issue, the other to come out in the next.他为忌个杂志写了两篇文章：一篇在本期发表，另一篇 在下一期刊载。
10. 动词不定式用于省略结构中
动词不定式用于感叹句
Oh, to be young again! ( = Oh, how happy I should be if I were young again!)啊，要能重返青春该多好呀！
动词不定式用于省略第一人称主语和动词be的简单句中
Glad to see you,很高兴见到你。
Hope to hear from you soon.希望不久收到你的来信。
动词不定式用于省略的疑问句中
What to do?做什么？
Where to go?到哪儿去？
How to get there?怎样才能到那里？