在 lest(以免)、for fear (that) (以防)、in case(以备万一)等之后也 要用 should+动词原形;在 advise, suggest, order,demand, request 等的从句中 should+do" 例如: It is necessary that he(should) be sent there at once. 有必要马上派他到那里去。 It is strange that he should say so. 他会说这样的话真是奇怪。 Let us go at once lest we should be late for the train. 我们马上走吧,以免赶不上火车。 情态动词 will 和 would 的用法 1)表示意志,决心或愿望。例如: Surely we will support all the people in the world in their strugglefor peace. 我们一定要支持全世界人民争取和平的斗争。 He would not let me try it .他不肯让我去试。 2)will 表示经常性、习惯性、倾向性,would 表示过去的习惯行为。 He will sit there hour after hour looking at the traffic go by. 他会经常一连几个小时坐在那儿观看来往的车辆。 He would come to see me when he was in Beijing. 他在北京时,常来看望我。 3)用于第二人称作主语的疑问句中,表示对对方的请求,would 的语气比 will 委碗 Would/will you kindly tell me the way to the station? 请问到火车站怎么走? 4)表可能性 This will be the book you are looking for. 这可能就是你要找的书。 She eould be about 60 when she died. 他死时大概 60 岁。 情态动词 need 和 dare 的用法 情态动词 need 实义动词 need 现 You need (not) do You (don't) need to do 在 时 He need (not) do He needs (doesn't need) to do 过 You needed (didn't need) to do 去 时 He needed (didn't need) to do 将 You need (not) do You will (not) need to do 来 时 He need (not) do He will (not) need to do 句型时态动词 情态动词 dare 实义动词 dare 肯定句现在时 dare to 少用 dare/dares to do 过去时 dare to 少用 dared to do 否定句现在时 daren't/dare not do do/does not dare (to) do 过去时 dared not do did not dare (to) do 疑问句现在时 Dare he do? Do you/Does he dear (to) do? 过去时 Dared he do? Did he dare (to) do needn't have v-ed 表示过去做了某事,但没有做的必要, 意为"本没必要…"。例如: You needn't have waken me up; I don't have to go to work today 表推测的情态动词句子的反意疑问句 He must/may be in the room, isn't he? He can't be in the room, is he? He must have finished the work, hasn't he? He may have done the work last night, didn't he? :情态动词+行为动词进行式 情态动词+行为动词进行式(即情态动词+ be + v-ing 形式),表示推测或评论某动作现在 是否正在进行。例如: 1)He must be playing basketball in the room. 2)She may be staying at home. 三、情态动词+行为动词完成进行式 情态动词+行为动词完成进行式(即情态动词+ have been + v-ing 形式),表示推测或评 论过去某动作是否正在进行或一直在进行。例如: 1)They should have been meeting to discuss the problem. 2)He may / might have been buying stamps in the post office when yousaw him. 某些情态动词的特殊用法 1.used to +v, be used to +v-ing 和 beused to +v (1)used to +v 意为"过去常常","过去一直";be used to +v-ing /n(名词)意为"习惯于 ";be used to +v 意为"被用来(做某事)"。 (2)used to 只表示过去,而 be used to +v-ing / n 可表示现在、过去或将来。例如: 1)He used to smoke. Now he doesn't. 2)He's quite used to hard work / working hard. 3)The knife is used to cut bread. 2.用作情态动词的其他短语 would rather, would sooner, would (just) as soon, had rather, hadbetter, had sooner, can not but, may (just) as well 等可用作情态动词。例如: 1)The soldier would sooner die than surrender. 2)The brave soldier would as soon die as yield to such an enemy. 3)I'd rather walk than take a bus. 4)If you don't like to swim, you may just as well stay at home. 注:这些短语后一般直接跟动词原形.would (had) rather,would (had) sooner, would (just) as soon 后可跟 that 引导的从句,that 常省去,从句要用虚拟语气。对现在和将来的假 设用过去时,对过去的假设用过去完成时。例如: 1)I would rather you came on Sunday. 2)I would sooner you hadn't asked me to speak yesterday. 二、动词不定式、动名词用法 ⒈不定式作主语 动词不定式作主语时,句子的谓语动词常用单数,其位置有以下两种: (1)把不定式置于句首。如: To get there by bike will take us half an hour. (2)用 it 作形式主语,把真正的主语不定式置于句后,常用于下列句式中。如: ①It+be+名词+to do It's our duty to take good care of the old. ②It takes sb+sometime+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 composition in a quarter of an hour. ④It+be+形容词+of sb+to do It is stupid of you to write down everything the teacher says. 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's kind of you to help me with my English.=You are kind to help mewith my English. ⒉动名词作主语 Learning without practice is no good. 动名词作主语时,也常用 It 句式。如: 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. ②It's+形容词+doing 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's important for you tokeep 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。 ⒊动词不定式和动名词作主语的区别 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: It's no good eating too much fat. It's no good for you to eat so much fat. ②动名词结构作主语,可以用名词或代词属格形式作逻辑主语。如: It's no use your pretending that you didn't know the rules. 二、作宾语 ⒈不定式作宾语 ①以下动词后,只能跟不定式作宾语。如:agree, ask, aim ,arrange,choose, decide, demand ,expect, fail ,help, hope, lean, long, manage, offer,plan, prepare, pretend, promise, refuse, wish 等,这些词大部分可接 that 引导的从句。如: 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 start back onfoot. When our visit to the farm was over, we expected that we would startback 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 foreign language well. He feels it his duty to help the poor. ③介词 but,except, besides+to do(do) 在这种句型中,如介词前有动词 do,后面应接不带 to 的不定式;如无 do,则接 to 不定式, 即带 do 不带 to, 带 to 不带 do。如: The enemy soldiers had no choice but to give in. On Sunday afternoon I had nothing to do but watch TV. ⒉动名词作宾语 ①以下动词后,只能接动名词作宾语,如:admit, appreciate, consider, delay, enjoy, finish ,keep, imagine,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 to your health. ②动名词作介词的宾语 I should go to attend the birthday celebration instead of staying at home. 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 time(in)doing, prevent/stop…(from)doing,there is no use(in)doing 等。 ⒊部分动词后面,既可接动词不定式,也可接动名词作宾语,意义不变。 如:begin, continue, start,hate, like, love, need, require, want 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 handwriting needs improving(to be 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。 在下列情况下,一般要用不定式: ①hate, like, love 前有 would(should)时,如:I'd like to have a cup ofcoffee. ②当谓语动词 begin, continue, start 等是进行式时,如:The students are starting to work on the difficult maths problem. ③begin, continue, start 与 know, understand 等状态动词连用时,如:I soon began to understandwhat was happening. ⒋advise, allow, encourage, forbid, permit 等动词后接动名词作宾语,或带不定式作宾 语补足语。如: Our teachers don't permit our swimming in the lake. Our teachers don't permit us to swim in the lake. ⒌部分动词后接不定式或动名词时,意义差别较大,应根据句子语境选择使用。 ①forget ,remember, regret 后接不定式,表示现在或未来的动作,接动名词表示动作已 经发生。如: 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 to attend themeeting. They regretted ordering these books from abroad. ②mean to do 打算做某事 doing 意味着…… 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 doing 试着做某事 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) doing 停止做某事 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…… to do 不能帮助干…… 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 roomfor you. ⑥go on to do 做不同的事或不同内容的事 doing 继续不停地做某事,指同一动作的继续 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 in the world. ⑦leave off to do 离开某地去干什么(目的状语) doing 停下某事 It's time to leave off talking and to start acting. They left off to go fishing. 三、做表语 不定式作表语表示具体动作或将来动作;动名词作表语表示抽象的一般行为。 ①To be kind to the enemy is to be cruel to the people. ②My chief purpose is to point out the difficulties of the 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, mistake, 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。 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 the people 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。 四、作定语 ⒈不定式作定语 不定式在句中作定语,置于被修饰的名词或代词之后。如: 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. 不定式短语作定语和被修饰词之间表示以下关系: (1)表示将来的动作(例①)。 (2)与被修饰词之间有动宾关系,如是不及物动词,则需加介词(例④)。 (3)与被修饰词之间有动宾关系,同时与句中其它词之间又有逻辑上的主谓关系时,尽管 有被动含义,却仍用主动语态(例③);如只有动宾关系,而无逻辑上的主谓关系,则需用被动语 态(例②)。 (4)不定式作定语时,一般可转换为定语从句,例①to arrive=that will arrive。 ⒉动名词作定语 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. 五、不定式作补足语 ⒈作宾语补足语 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。 (1)常要求不定式作宾补的动词有:allow, ask, advise, beg,cause, drive(强 迫),encourage, expect, forbid,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,discover, find(=consider),feel(=think),imagine, judge, know, prove, think,suppose, see(=understand),understand 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 to have been foolish. (3)感觉动词和使役动词后用作宾补的不定式须省略 to。 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:The students are made to do too much homework every day. (4)help, know 后面的"to"可有可无。如: Would you please help me(to) fill in the tax form? I've never known her(to)be late before.但:Hewas known to have been to France before. (5)部分短语动词后,常接不定式作宾补,如: 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。 ⒉作主语补足语 不定式作主语补足语,和主语构成一种逻辑上的主谓关系。如: ①He was not allowed to enter the classroom for being late. ②The young university student is considered to have great promise. 六、不定式作状语 ⒈作目的状语 (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 to forget 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 what would 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 the students The room is really comfortable tolive in. 常这样用的形容词有:comfortable, easy, dangerous, difficult, expensive, fit, impossible 等。 ⒉作结果状语 We came home after our holiday to find our garden neat and tidy. 不定式作结果状语还常用在下列句式中。如: 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. ②enough…to The speed is high enough for us to catch up with the first liner. ③only to Jane hurried back only to find her mother dying inthe hospital. ④too…to I'm too tired to stay up longer. 但在下列结构中,too…to 并非是"太……而不能……"之意。如: 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) ②We have too much to learn.我们要学的太多了(不定式作定语)。 ⒊不定式短语还可作独立成分,用于句首、句中或句末。如: 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),tobe sure(真的)等等。 七、动词不定式、动名词的其它用法 ⒈疑问词+不定式结构 疑问词 who, what, which, when, where, whether, how 后可接不定式构成不定式短语, 在句中作主语、宾语、表语等。如: 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 could learn… 经常在这种结构中使用的动词有:consider, decide, discover, explain, find out, forget, hear, know,learn, observe, understand, wonder 等。 ⒉动词不定式的时态、语态 (1)时态 ①一般式:动词不定式一般式表示的动作发生在谓语动词之后,有时表示同时发生。如: I hope to become a university student this year.(to become 发生在 hope 之后) We often hear Dick play the piano in the next room.(play 和 hear 同时发生) ②完成式:表示的动作发生在谓语动词所表示的动作之前。如: I'm sorry to have kept you waiting. We are too young to have seen the old society. ③进行式:表示的动作与谓语动词同时发生。如: The teacher happened to be correcting our papers when I came in. They seemed to be discussing something important. (2)语态 如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者,不定式一般要用被动 语态形式。如: 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 thingsto take 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 isnothing to be done now.(We can do nothing now.) ⒊动名词的时态、语态 (1)时态 ①一般式:动名词的一般式所表示的动作可以是泛指,也可与谓语动词同时发生,或发生 在谓语动作之前、之后。如: We are interested in collecting stamps. I shall never forget seeing the Great Wall for the first time. We are not afraid of dying. ②完成式所表示的动作发生在谓语动词之前。如: Lmagine having travelled on the moon. We were praised for having finished the work ahead of time. (2)被动语态 ①如果动名词的逻辑主语为动名词所表示的动作的承受者,动名词要用被动语态,动名 词的被动语态有一般式与完成式之分。如: The young man came in without being noticed. He prided himself on having never been beaten in class. ②有些动词后的动名词用主动形式,但表示被动意义。如: The bike needs repairing. If a thing is worth doing, it is worth doing well. ⒋在口语中,为避免重复,常用"to"代替不定式结构,有时甚至可以把 to 省略。如: 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? -OK, I'll try. 另外,be going to, ought to, used to 等也常用于这一结构中。 ⒌在 why 引起的问句中,省略"to"。如: Why spend such a lot of money? Why not wait for a couple of days? ⒍当两个或更多作用相同的不定式并列使用时,只在第一个不定式前加"to"。如: It's quite necessary for us to read more and have more practice. ⒎"to"在下列短语中是"介词",后接动名词或名词形式。如: devote…to, face up to(勇敢地面对),lookforward 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。