1、Section Grammar动词不定式&but动词不定式语 境 自 主 领 悟先观察原句后自主感悟1.Scientists have tried many ways to solve this problem and in China，a mass campaign has been started to help solve it.2.They are often so thick that you cannot see the sun，and the wind is sometimes strong enough to move sand dunes.3.There was nothin
2、g to be done.It was the most frightening and the most dangerous situation Ive ever been in.4.Sandstorms in China appear to have increased in recent years as a result of “desertification”.5.The storms sometimes continue all day and traffic moves very slowly because the thick dust makes it difficult t
3、o see.6.When a sandstorm arrives in the city，weather experts advise people not to go out.7.The winds are very strong.Its difficult to breathe and the dust makes me ill.8.To prevent it coming nearer，the government is planting trees.9.And yet we do nothing but talk about it.1.1句中，第一个和第二个不定式在句中分别充当状语和宾
4、语；2句和8句中的不定式作状语；5句中，it为形式宾语；7句中，it为形式主语。2.由6句可知，不定式的否定式为not to do。由3句可知，不定式的被动式为to be done。由4句可知，不定式的完成式为to have done。3.由9句可知，不定式在介词but后面时，如果but之前有行为动词do的各种形式，则介词后的不定式不带to，否则带to。一、动词不定式1动词不定式的时态和语态时态语态主动被动一般式to doto be done进行式to be doing/完成式to have doneto have been done(1)不定式的一般式：表示不定式的动作与谓语动词同时(几乎同
5、时)发生或在谓语动词之后发生。He asked me to help him with the task.他让我帮他完成这项任务。(2)不定式的进行式：表示不定式的动作正在进行且与谓语动词同时发生。He is said to be studying abroad but I dont know which country it is.据说他正在国外学习，但我不知道是哪个国家。(3)不定式的完成式：表示不定式的动作发生在谓语动词之前。The engine just wont start.Something seems to have gone wrong with it.发动机发动不起来了。似乎
6、出问题了。(4)不定式的被动式：当动词不定式的逻辑主语是动词不定式所表示的动作的承受者时，一般使用动词不定式的被动形式。There are still many problems to be solved before we are ready for a long stay on the Moon.在我们准备在月球上长住之前，还有很多问题需要解决。2动词不定式的语法功能(1)作主语当不定式作主语时，表示一次具体的动作，并且常用it作形式主语，把不定式后置。No matter how bright a talker you are，there are times when its better
7、 to remain silent.无论你是多么健谈的人，有些时候保持沉默更好。名师点津不定式作主语时谓语动词通常用单数形式。(2)作表语不定式作表语一般表示具体动作，特别是表示将来的动作。At college，Barack Obama didnt know that he was to become the first black president of the United States of America.在大学时，贝拉克奥巴马不知道他会成为美国第一任黑人总统。如果主语是以aim，duty，hope，idea，job，plan，problem，purpose，thing，wish等为
8、中心的名词，或是what引导的名词性从句，不定式作表语用来说明主语的内容。Her wish is to become a key college student after graduation.她的愿望是毕业后成为一名名校大学生。(3)作宾语常用带to的不定式作宾语的动词有afford，agree，ask，decide，expect，hope，learn，manage，offer，pretend，promise，refuse，want，wish等。She seated herself at a small table in the restaurant，waiting to be serve
9、d.她坐在餐馆里的一张小桌子旁等着被服务。有些动词后面可以跟不定式作宾语，也可以跟动名词作宾语，但意思不同，如forget，remember，try等；有些动词后面接不定式和动名词作宾语时意思差别不大，如start，begin，hate，like 等。I remembered to lock the door before I left the office，but forgot to turn off the lights.我离开办公室之前记得锁门却忘记关灯了。名师点津feel，find，think，believe，consider，make这几个动词后面接不定式作宾语，且宾语后面有形容词/
10、名词作宾补时，常用it作形式宾语，而把不定式放到宾补之后。We think it quite important for us to learn a foreign language well.我们都认为学好一门外语对我们来说非常重要。(4)作宾语补足语不定式作宾语补足语，常用于下列动词后：ask，cause，call，help，force，allow，permit，advise，order，get，want，wish，tell等。Passengers are permitted to carry only one piece of hand luggage onto the plane.乘客
11、只允许携带一个手提行李包登机。名师点津(1)在“五看(see，watch，observe，notice，look at)三使(make，let，have)两听(hear，listen to)一感(feel)” 等动词后作宾语补足语的动词不定式不带to，但当以上动词(let，have除外)用于被动语态时需要带to。Let those in need understand that we will go all out to help them.让那些需要帮助的人们明白我们会全力以赴去帮助他们。The person was seen to enter the shop by us.我们看见那个人进
12、了商店。(2)help后跟不定式作宾语补足语时，不定式可带to也可不带to，即help sb.(to) do sth.。(5)作定语不定式作定语，置于被修饰词之后，常表示未发生的动作。The airport to be completed next year will help promote tourism in this area.明年将竣工的机场将会帮助推进该地区旅游业的发展。中心词是序数词或被序数词、最高级、 only等修饰时，用不定式作定语。He is always the first to arrive at the school and the last to leave the
13、 school.他总是第一个到校，最后一个离校。常用不定式作定语的名词：promise，plan，offer，decision，ability，warning等。The ability to express an idea is as important as the idea itself.表达观点的能力与观点本身同等重要。名师点津被修饰的名词与不定式存在被动关系时，不定式的动词必须是及物动词，若为不及物动词，则后面必须要有适当的介词。Suddenly a good idea occurred to her，but she couldnt find any paper to write on
14、.突然她想到了一个好主意，但是她找不到写下它的纸。(6)作状语原因状语。不定式作原因状语时，通常位于情感类形容词或表示心理活动的形容词/过去分词之后，表示产生某种情感或心理活动的原因。We were astonished to find the temple still in its original condition.令我们吃惊的是，这座寺庙仍保持着最初的样子。目的状语。不定式作目的状语时可位于句首和句末，且不定式前可加in order/so as，但so as to不能位于句首。To make it easier to get in touch with us，youd better k
15、eep this card at hand.为了更容易与我们取得联系，你最好把这张卡片放在手边。The boy worked very hard in order to/so as to make up for the lost time.这个男孩工作非常努力，为的是弥补失去的时间。结果状语。不定式作结果状语常表示意外的结果，常在不定式前加only。I arrived at the shop only to find I had left all my money at home.我到了商店却发现钱全落在家里了。 3不定式用主动形式表示被动意义的常见情况(1)在“主语系动词表语(形容词)(fo
16、r sb.) to do” 结构中，句子的主语与构成不定式的动词有逻辑上的动宾关系，不定式用主动形式表示被动意义。该结构中常用的形容词有easy，hard，difficult，fit等。The book is so difficult to understand that I want to give it up.这本书如此难懂以至于我不想读了。(2)不定式作定语时，若构成不定式的动词与不定式所修饰的词之间为动宾关系，并且句子的主语是不定式动作的发出者时。He has a large family to support.他有一个大家庭要养。(3)在“too.to.” 和“enough.to.”
17、 结构中，若构成不定式的动词与句子的主语之间为动宾关系，不定式可以用主动形式表示被动意义。The book is cheap enough to buy.这本书很便宜，可以买。The maths problem is too difficult for me to work out.这道数学题太难我不能解出它。(4)在“特殊疑问词to do” 结构中，do与特殊疑问词之间为动宾关系时，不定式常用主动形式。I dont know what to do next.我不知道接下来该做什么。即时演练1单句语法填空He seems to understand (understand) what I sa
18、id.When I came in，he pretended to be reading (read)It is difficult for him to get(get) along with other kids of his age.二、but动词不定式1当but(表示“除之外”)前有实义动词do的某种形式时，其后的不定式通常不带to。其他情况不定式通常都要带to。If he takes on this work，he will have no choice but to meet an even greater challenge.(have no choice but to do.别
19、无选择只好做)他如果接受这项工作的话，必然会遇到更大的挑战。He does nothing but complain，which bothers almost everyone around him.他除了抱怨无所事事，这让他周围的几乎每个人都烦。2but用于cant but，cant help but，cant choose but等短语后，意为“不得不，只能”，不定式不带to。We cant but face the reality.我们只能面对现实。I couldnt choose but speak the truth.我不能不说真话。Whenever I think of the s
20、tory，I still cant help but laugh at myself.每当我想起我那个故事，我就会忍不住地笑起自己来。即时演练2单句改错I cannot but to admire your decision.去掉toHe has nothing to do but watching TV at home.watchingwatchWhen the streets are full of melting snow，you cant help but got your shoes wet.gotget.单句语法填空1The weather seems to be improvin
21、g(improve) now.Lets go for a picnic.2All through the morning，Mary did nothing but sit(sit) on the sofa，watching TV.3Although it is a hard task to protect our environment，we cant help but go(go) ahead.4When I returned to Beijing from Shanghai，the sandstorm had just ended.My friends all said I was luc
22、ky to have missed(miss) it.5Were having a meeting in half an hour.The decision to be made (make) at the meeting will influence the future of our company.6He promised to help(help) us whenever we were in trouble.7To catch (catch)the early flight，we ordered a taxi in advance and got up very early.8It
23、seems that we have no choice but to wait(wait)9Its silly of you to have left (leave) your bike outside unlocked.10Id rather read than watch television; the programs seem to be getting(get) worse all the time.单句改错1As there was no bus，he couldnt but to walk home.去掉to2For example，when I ride my bike，my
24、 parents wont let me to ride by myself.去掉to3Only this man was strong enough lift the heavy stone.lift前加to4The question be discussed next year has something important to do with our daily life.be前加to5The mother did what she could rescue her son，although she herself was in danger.rescue前加 to6They had
25、no choice but obey the school rules.obey前加to7He preferred to surf the Internet，but his parents told him not.not后加to8We thought impossible to finish the task in one day.thought后加it9When it comes to my study，he is very strict and will never let me to be lazy.去掉me后的to10His mother cant help but to feel embarrassed in front of so many people.去掉but后的to
