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1、“be to do” 的用法一般说来，“be to do” 这个结构有两种语法意义，其一是连系动词be+动词不定式做表语，其二是be to是一个独立词汇单位,具有情态含义,可以把它叫做情态习语(modal idiom)。 一、be +动词不定式, 不定式做表语,表示主语和表语在概念上是等同的。如： The problem is to find a solution. His plan is to clean the room. My wish is to be a doctor. 二、be to +动词不定式中的be to用作情态习语, 这时的be to do表示: “计划”、“安排”、“义务
2、”、“应该”、“可能”、“命运”等。(have to, ought to)。如: He is to have a holiday. (表示将来) The committee is to meet today. (表示计划、安排) You are to go to the hotel where rooms have already been booked for you. 1. 表示 “将”、“计划”、“安排”。(意思接近于be going to) 如： Their daughter is to get married soon. Who is to question him？ It was
3、the last film at the cinema，which was to close next day. After dinner they were to go to a movie. was/ were to do 表示过去曾经计划要做的事，或者过去应当做的事，而且从现在的角度来看已经实现了。如： I felt nervous because I was soon to leave home for the first time. I was to play Juliet. The expedition was to start in a weeks time. was/ were
4、 to have done, 表示 “本打算”、“本计划”或“本应当” 做的事而没有做成或没有发生。如: I was to have seen him last Wednesday, but he didnt come. We were to have been married last year. 2. 表示 “义务”、“应该” 。(意思接近于should， must， ought to， have to) 如： No one is to leave the building. 谁也不得离开这楼房。 You are not to smoke in this room.=You are not
5、 supposed to smoke in this room. You are to be back by 10 oclock. 你必须十点以前回来。 3. 表示可能性, 相当于can, may 如: Such books are to be found in the library. 这样的书在图书馆里就能找到。 Not a single sound was to be heard. 一点儿声音也听不到。 Not a soul was to be seen. 看不到一个人影。 She was nowhere to be found. 哪儿也找不到她。 She was never to se
6、e his wife and family again. 5. 表示 “命运”, 将来必然要发生的事, 译作 “注定”。如： He came to power, but he was to play dearly for it: soon he was assassinated. The worst is still to come. They said goodbye, little knowing they were never to meet again. 6. 用于“ifwere to do”，表示虚拟语气。如： If it were to rain tomorrow, the spo
7、rts meeting would be put off. 如果明天下雨, 运动会就会延期。一、时态、语态 时态、语态需要掌握的要点： 1.以下几类动词一般不能用于进行时，同样不用于完成进行时： (1)表示感知的动词：hear, feel, notice, recognize, see, taste, smell； (2)表示意愿、情感的动词：desire, dislike, forgive, hate, like, love, prefer, refuse, want, wish, fear, love, hate； (3)表示思考、看法的动词：believe, doubt, expect,
8、 forget, hope, feel, mean, know, agree, realize, mind, recall, recollect, remember, trust, suppose； (4)表示所有、占有的动词：belong to, owe, own, possess, hold(容纳)； (5)其他动词：cost, appear, concern, contain, consist, deserve, matter, seem。 如： Id say whenever you are going after something that is belonging to you,
9、 anyone who is depriving you of the right to have it is criminal. (1997年考研题， belong表示归属，不用于进行式) He was seeing somebody creeping into the house through the open window last night. (1990年考研题，see表示结果，不用于进行式) 2. 不用will/shall表达将来时的形式： (1)be going to表示现在的打算和意图； (2)arrive, come, drive, go, leave, retire, r
10、eturn, set off, start, take off等表示移位的动词的进行体表示按计划肯定要发生的将来动作； (3)be to (do)表示安排、计划、决定、命令或注定要发生的事，如： Greater efforts to increase agricultural production must be made if food shortage is to be avoided. (4)be about to (do)表示将要(做)，如： Marlin is a young man of independent thinking who is not about to pay co
11、mpliments to his political leaders. (5)be on the point /verge of (doing)表示“马上就要”，一般不与表示将来的时间状语连用； (6)be, begin, come, depart, get off, go, leave, return, start的一般现在时表示按日历或时刻表要发生的将来动作或事件，如： If you want your film to be properly processed, youll have to wait and pick it up on Friday, which is the day a
12、fter tomorrow. (画线部分一般不用will be) (7)在时间、条件、让步从句中，一般现在时代替将来时，但要注意区别从句的类型，如： I dont know where he will go tomorrow. 我不知道他明天去哪儿。(宾语从句) Ill tell him when you will ring again. 我告诉他你什么时候再来电话。(宾语从句) 比较：Ill tell him when you ring again.你再打电话时我告诉他。(状语从句) (8)在make sure, make certain, see (to it) 后的that从句中，谓语动
13、词用一般现在时代替将来时，如： See to it that you include in the paper whatever questions they didnt know the answer to last time. (include 不能用will include或其他形式) 3.完成时是时态测试的重点，注意与完成时连用的句型和时间状语： (1)by/between/up to/till +过去时间、since、by the time/when +表示过去发生情况的从句，主句用过去完成时。如： We had just had our breakfast when an old
14、man came to the door. Between 1897 and 1919 at least 29 motion pictures in which artificial beings were portrayed had been produced. (表示1919年时已发生的情况) (2)by +将来时间、by the time/ when +谓语动词是一般现在时的从句，主句用将来完成时。如： By the time you arrive in London, we will have stayed in Europe for two weeks. I hope her hea
15、lth will have improved greatly by the time we come back next year. (3)by now、since +过去时间、in/during/for/over/the past/last few(或具体数字)years/days/months，主句用现在完成时, 但在it is +具体时间since/before这一句型中，主句更多的时候不用完成时。如： The changes that howe taken place place in air travel during the last sixty years would have
16、seemed completely impossible to even the most brilliant scientists at the turn of the 19th century. It is four years since John left school. (4)在It is the +序数词/形容词最高级+that的定语从句中，谓语动词常用现在完成时。如： It isnt the first time that I have found myself in an embarrassing situation. (5)在no soonerthan, hardly/sca
17、rcelywhen/before句型中，主句常用过去完成时。 (6)其他与完成时连用的时间状语：all this while, all this year, for some time, so far, already, before, just, long, yet等。 4.完成进行时指动作在完成时的基础上还要继续下去。如： The company has been promising a rise in salary for ages, but nothing has happened. The school board listened quietly as John read the
18、demand that his followers had been demonstrating for. 时态、语态答题思路： (1)先根据选项的区别点确定考题要点为时态，然后回到题句中寻找给出的或暗示的时间状语，缩小选择范围，进而选出正确答案； (2)根据谓语动词与句子主语或非谓语动词与其逻辑主语的关系，确定句子是主动语态还是被动语态。 二、不定式 1.不定式做主语 (1)做形式主语的代词： 不定式做主语, 通常用it充当形式主语, 把做主语的不定式短语后置。如： It took me only five minutes to finish the job. To be frank, it
19、 is a great relief to have the task fulfilled in so short a time. (2)引导逻辑主语的介词： 不定式的逻辑主语一般由介词for引导,但下列表示人的性格行为特征的形容词做表语时, 不定式的逻辑主语则由of引导： absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind, thoughtful, considerate, greedy, generous, honest, mod
20、est, polite, rude, cruel, selfish, lazy, wicked, wrong。如： Experts say walking is one of the best ways for a person to stay healthy. Its clever of you to have invented such a device. (3)不定式做主语补足语： 掌握常用不定式做主语补足语的句型。注意不定式表示的动作发生的时间，并采用相应形式。如： said reported thought be to do sth. believed known supposed
21、Byron is said to have lived on vinegar and potatoes. The bank is reported in the local newspaper to have been robbed in broad daylight yesterday. 2.不定式做宾语 (1)必须接不定式做宾语的动词： 掌握要求接不定式做宾语的动词： agree, afford, aim, arrange, appear, ask, attempt, choose, claim, decide, desire, determine, expect, fail, guara
22、ntee, hope, endeavor, intend, long, mean, manage, offer, ought, plan, pledge, pretend, prepare, promise, proceed, prove, resolve, refuse, request, swear, tend, try, venture, wait, wish。如： Even though the children pretended to be asleep, the nurses were not deceived when they came into the room. 注意:
23、1)有的动词要求特殊疑问词+不定式做宾语, 这类动词有： consider, discover, explain, forget, guess, know, learn, observe, remember, see, tell, understand, wonder，如： While still a young boy, Bizet knew how to play the piano well and as he grew older, he wrote operas, the most famous of which is Carmen. 2)如果该特殊疑问词在不定式中做介词宾语, 介词
24、往往置于该特殊疑问词的前面。如: The professor can hardly find sufficient grounds on which to base his argument in favor of the new theory. Without facts, we cannot form worthwhile opinion for we need to have factual knowledge upon which to base our thinking. (2)可以用不定式做宾语补足语(复合宾语)的动词： 下列动词可以用不定式做宾语补足语(复合宾语)： advise
25、, allow, ask, beg, cause, command, compel, enable, determine, encourage, expect, feel, find, force, hate, have, hear, help, inform, invite, let, like, make, mean, need, notice, notify, oblige, order, permit, persuade, remind, request, require, see, send, teach, tell, tempt, trouble, urge, want, warn
26、, watch, wish。 注意：画线动词后面的不定式不带to。 如： Because of the recent accidents, our parents forbid my brother and me to swim in the river unless someone agrees to watch over us. 3.不定式做定语 (1)被修饰的名词前有序数词、形容词最高级或next, last, only, not a, the, very等限定词时，该名词用不定式做定语。如： the first woman to set foot on the moon 第一个登上月球
27、的女性 (2)如果其动词要求不定式做宾语，相应的名词一般用不定式做定语。如： tendency to dotend to do, decision to dodecide to do This book is an attempt to help you use English and recognize how it is used. (3)如果其形容词形式要求接不定式做补语，相应的名词一般用不定式做定语。如： ambition to do “干的雄心”be ambitious to do“有雄心干” curiosity to do “对的好奇心”be curious to do“对好奇”
28、ability to do“做的能力”able to do“有能力做” According to Darwin, random changes that enhance a species ability to survive are naturally selected and passed on to succeeding generation. (4)表示方式、原因、时间、机会、权利等名词用不定式做定语，这些名词包括： way, method, reason, time, place, chance, occasion, opportunity, evidence, power, rig
29、ht, movement, drive (运动)，effort等。如： I worked so late in the office last night that I hardly had time to catch the last bus. We appreciate your efforts to bring about a comprehensive solution to the existing problem. (5)不定代词something, nothing, little, much, a lot习惯上用不定式做定语。如： Though we have made grea
30、t progress, there is still much to be improved. 4.不定式做状语 不定式做状语主要表示目的、程度、结果、方式。 (1)in order to(do), so as to(do)结构引导目的状语，so as to不能置于句首。如： To succeed in a scientific research project, one needs to be persistent . I advise them to withdraw so as not to get involved. (2)soas to, suchas to, enoughto, t
31、ooto结构做程度状语。如： The solution works only for couples who are self-employed, dont have small children and get along well enough to spend most of their time together. The vocabulary and grammatical differences between British and American English are so trivial and few as hardly to be noticed. (3)不定式做结果状语只能出现在句子的末尾，表示不愉快的结果，有时用