To get there by bike will take us half an hour.
It's our duty to take good care of the old.
②It takes sb+some time+to do
How long did it take you to finish the work?
③It＋be＋形容词＋for sb＋to do
It is difficult for us to finish writing the compositionin a quarter of an hour.
④It＋be＋形容词＋of sb＋to do
It is stupid of you to write down everything the teachersays.
⑤It seems(appears)＋形容词＋to do
It seemed impossible to save money.
在句型③中，常用表示客观情况的形容词，如：difficult,easy,hard,important,impossible,necessary 等；在句型④中，常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词。在不定式前的sb，可看作其逻辑主语。这一句式有时相当于Sb is＋形容词＋to do句式 ，如：It'skind of you to help me with my English.=You are kind to helpme with my English. 字串5
Learning without practice is no good.
①It's +no good(no use,fun,a pleasure,a waste of time)+doing…
It's no good reading in dim light.
It's no use sitting here waiting.
It's dangerous swimming in the sea in windy days.
这样用的形容词有expensive,nice,tiring等，但important,necessary则不适用于这种结构，应用不定式 代替，如：It'simportant for you to keep fit.
③There is no+doing
There is no saying what will happen next.
在这一结构中，动名词后常带宾语，相当于"It's impossible to…"结构。
①不定式作主语经常表示具体动作，常与特定的动作执行者联系在一起；而动名词作主语经常表示抽象动 作，经常不与特定的动作执行者联系在一起。如： 字串8
It's no good eating too much fat.
It's no good for you to eat so much fat.
It's no use your pretending that you didn't know the rules.
I decided to ask for my money back.
I decided that I would ask for my money back.
When our visit to the farm was over,we expected to startback on foot.
When our visit to the farm was over, we expected that wewould start back on foot.
②当复合宾语中的宾语是不定式时，先用形式宾语it代替不定式，把不定式置于补语之后，即：主语＋动 词＋it＋补语＋to do句式。如：
We think it quite important for us to learn a foreignlanguage well.
He feels it his duty to help the poor.
The enemy soldiers had no choice but to give in.
On Sunday afternoon I had nothing to do but watch TV.
①以下动词后，只能接动名词作宾语，如：admit,appreciate,consider,delay,enjoy,finish,keep,imag ine,mind,miss,practise,resist,risk,save,suggest,don't mind,give up,insist,on, put off等。如：
I suggest spending our summer vacation in a seaside town.
You must give up smoking, for it does too much harm toyour health.
I should go to attend the birthday celebration instead of staying at home. 字串8
What about inviting Li Jun to make a speech?
动名词前的介词有时可以省略，如：have difficulty(in)doing,have no trouble(in)doing,lose no ti me(in)doing,prevent/stop…(from)doing,there is no use(in)doing等。
在need,require,want后接-ing形式，表示被动意义，也可接不定式，但要用被动形式，如：Your handwr iting needs improving(tobe improved). hate,love,like接不定式表示特定的未来事件，接动名词表示目前 正在进行的活动或一般的行为。
①hate,like,love前有would(should)时，如：I'd like to have a cup of coffee.
②当谓语动词begin,continue,start等是进行式时，如：Thestudents are starting to work on the di fficult maths problem.
③begin,continue,start与know,understand等状态动词连用时，如：I soon began to understand what
Our teachers don't permit our swimming in the lake.
Our teachers don't permit us to swim in the lake.
Don't forget fo post the letter for me.
Have you forgotten meeting her in Beijing Airport?
Remember to close the windows before you leave.
I remember writing him a letter a year ago.
We regret to tell you that all of you are not invited toattend the meeting.
They regretted ordering these books from abroad.
②mean to do 打算做某事
I meant to catch up with the early bus.
This means wasting a lot of money.
③try to do 设法尽力做某事
You should try to overcome your shortcomings.
Try working out the physics problem in another way.
④stop to do 停下一件事去做另一件事（不定式作目的状语）
On the way to the airport,I stopped to buy a paper.
You'd better stop arguing and do as you are told.
⑤can't help doing 禁不住……
They couldn't help jumping up at the news.
Sorry I have lots of work to do.So I can't help to make up the room for you.
⑥go on to do 做不同的事或不同内容的事
He went on to talk about world situation.他接着又谈了世界形势。
We'll go on fighting so long as there is oppression inthe world.
⑦leave off to do 离开某地去干什么（目的状语）
It's time to leave off talking and to start acting.
They left off to go fishing.
①To be kind to the enemy is to be cruel to the people.
②My chief purpose is to point out the difficulties ofthe matter.
③What I would suggest is to put off the meeting.
当主语和表语都是不定式时，其含义一是条件，一是结果（例①）。当主语是aim,duty,hope,idea,mista ke,plan,purpose,suggestion等为中心词的名词词组（例②）时，或以what引导的名词性分句（例③），不定 式说明主语的内容。 字串7
④Our work is serving the people.
⑤What he likes is taking a walk after supper.
⑥The story told by Mr.Wang is interesting.
④⑤句动名词作表语，与主语部分可以转换，如Serving thepeople is out work,而⑥句中是现在分词作 表语，说明主语的性质、状态，现在分词具有形容词的各种特征，另外，动名词作表语还应与进行时态区别开 来。
①The next train to arrive is from Washington.
②Have you anything to be taken to your sister?
③Do you have anything to say on the question?
④Would you please give me some paper to write on?
⑤My wish to visit France has come true at last.
(4)不定式作定语时，一般可转换为定语从句，例①to arrive=that will arrive。
①This passage can be used as listening materials.
②The reading room of our school library can hold 800people.
③All moving bodies have energy.
①②句动名词作定语说明一种性能，即：用来……的；第③句为现在分词作定语，单个分词作定语常置于 被修饰词之前，与被修饰词之间，可构成逻辑上的主谓关系，分词短语作定语常置于被修饰词之后。如：The man standing at the school gate is Professor Hua.
一些及物动词除要求按宾语外，有时还需要有宾语补足语，说明宾语的行为、状态、特征，这时意思才相 对完整。 字串2
(1)常要求不定式作宾补的动词有：allow,ask,advise,beg,cause,drive（强迫），encourage,expect,fo rbid,force,get,would like(love,hate),order,permit,persuade,teach,tell,want,warn,wish等。如：
①Would you like me to give your regards to Mary?
②I want you to understand the whole passage clearly.
(2)部分动词后常接to be＋形容词、名词短语等形式，有时to be可省略，如：believe,consider,discov er,find(=consider),feel(=think),imagine,judge,know,prove,think,suppose,see(=understand),understa nd等。
①We all believe John(to be)honest.
②I consider him(to be)one of the best biology teachers of No. 1 Middle School.
但当不定式是完成式时，to不能省略，如：We consider him tohave been foolish.
①I didn't hear anyone say anything about it.
②They make the students do too much homework every day.
这种句式在变为被动语态时，to不能省略，如第②句：Thestudents are made to do too much homework
Would you please help me(to) fill in the taxform?
I've never known her(to)be late before.但：He was known to have been to France before.
You may depend on them to be there early.
The Party calls on us to increase production and practise economy.
常这样用的短语动词有：ask for,care for,call on,count on,depend on,wait for,long for（渴望）， prepare for,wish for等。
①He was not allowed to enter the classroom for being late.
②The young university student is considered to have great promise.
(1) ①I stayed there to see what would happen.
②Henry has decided to go to the hospital to be examinedby the doctor.
(2)有时为了强调，不定式前可加in order或so as。如：
Bob took down my telephone number so as(in order)not toforget it.
有时为强调目的状语可把in order to或不定式置于句首，但so as to不能这样用。在这种句式中不定式部 分可转换为so that,in order that,成为目的状语从句，如：
I stayed there so that (in order that)I could see whatwould happen.
(3)在部分表示感情色彩的形容词、过去分词或动词之后可接不定式，如：astonished,glad,happy,laugh ,pleased, sad,smile,sorry,surprised等。
①We are glad to hear the news.
②I was surprised to see that a three-year-old baby could write so well.
在部分形容词后接不定式，用主动形式表示被动意义，这种句型中的主语是不定式的逻辑宾语。如：The question raised by thestudent is difficult to answer. 字串2
The room is really comfortable to live in.
We came home after our holiday to find our garden neat and tidy.
①so…as to;such…as to
I'm not so stupid(a fool) as to put it in writing.我不至于愚蠢到会把它写下来。
I'm not such a stupid fool as to put it in writing.
The speed is high enough for us to catch up with thefirst liner.
Jane hurried back only to find her mother dying inthehospital.
I'm too tired to stay up longer.
①I'm only too glad to have passed the exam.考试及格我太高兴了。（too修饰glad to have…，相当 于very） 字串2
②We have too much to learn.我们要学的太多了（不定式作定语）。
To tell the truth,the play was a great disappointment tome.
常见的短语有to be exact（确切地说），to begin with（首先），to do him justice（说句对他公道的 话），to be sure（真的）等等。
①When to leave for London has not been decided yet.
②Mr. Smith didn't know whether to leave or stay there.
③I asked Professor Xu how to learn English well.
④The question was where to get the medicine needed.
以上例句中疑问词＋不定式部分，均可转换为相应的从句形式。如：①When we shall leave…③…how I 字串2
经常在这种结构中使用的动词有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等。
I hope to become a university student this year.（tobecome发生在hope之后）
We often hear Dick play the piano in the next room.（play和hear同时发生）
I'm sorry to have kept you waiting.
We are too young to have seen the old society.
The teacher happened to be correcting our papers when Icame in.
They seemed to be discussing something important.
It's a great honour to be invited to Mary's birthday party.（不定式作主语）
It was impossible for lost time to be made up.（不定式作主语）
I wish to be sent to work in the country.（不定式作宾语）
Can you tell me which is the car to be repaired?（不定式作定语）
He went to the hospital to be examined.（不定式作状语）
在There be结构中，修饰主语的不定式可用被动，也可用主动。如：There are still many things to t ake care of (to be taken care of).但有时两种形式表达的意思不同，如：These is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)
We are interested in collecting stamps.
I shall never forget seeing the Great Wall for the firsttime.
We are not afraid of dying.
Lmagine having travelled on the moon.
We were praised for having finished the work ahead of time.
The young man came in without being noticed.
He prided himself on having never been beaten in class.
The bike needs repairing.
If a thing is worth doing, it is worth doing well.
①—Did you go to visit the Great Wall?
—No,I wanted to,but there wasn't enough time.
②—Would you like to come to a party?
—I'd love to.
③—Don't make any mistakes in your homework,will you?
—I'll try not to.
④—Try to be back by 12,won't you?
另外，be going to,ought to,used to等也常用于这一结构中。
Why spend such a lot of money?
Why not wait for a couple of days?
It's quite necessary for us to read more and have morepractice.
devote…to,face up to（勇敢地面对），look forward to（盼望），object to（反对），take to（养 成习惯，对……感兴趣；开始从事某种活动），be used to（习惯于）等。 字串3