教师版2011届高考英语二轮专题讲练测专题7虚拟语气和情态动词(教学案).doc

2012届二轮专题讲练测 虚拟语气和情态动词一、【考情分析】英语中常用的情态动词主要有can，could，may，might，must，will，would，shall，should，ought to，dare，need，used to，had better等。在学习情态动词时应注意以下几点：同一情态动词表示不同的意义的情况；情态动词后跟各种形式的用法；特别是注意“情态动词+完成式”是高考中的重点所在。高考中的虚拟语气一般与情态动词结合进行考查。每年高考试题中都会出现一定的题目。二、【思维导航】l.系统复习情态动词。掌握情态动词的基本用法。学习和掌握情态动词的意义和用法，应遵循如下步骤：(1)系统复习情态动词，从整体上把握情态动词的语法特征和语意特征；(2)逐个学习，了解每个情态动词的用法特征；(3)认真区别有相同功能的、意思相近的情态动词的用法(4)收集大量真实的口语材料(如教材中的对话材料及听力材料)，在真实的交际情景中印证和领悟它们的用法和特征。2体会说话者的语气和态度，注意和情态动词的区别。情态动词表示说话者的态度和语气。解答情态动词类的题目时，一定要细细领会情景特征，体会说话者的语气，情景中没有废话，不要放过任何细节。只有这样，才会找到有效信息，做出最佳选择。例如：This printer is of good quality. If it _ break down within the first year, we would repair it at our expense.A. would B. should C. could D. might【答案】B【解析】考查虚拟语气用法。前句表示打印机质量好，按道理起初的一年内不可能毁坏，所以下句提出了一种将来的可能性不大的假设，由此判断为与将来事实相反的假设，用虚拟，从句形式Be to do, 动词过去时；should 动词原形。故选B.3.掌握虚拟语气规律使用正确的表达形式。虚拟语气通常用在一些特定的句型中，在advise，demand，order，request，suggest，propose，require，recommend等的宾语从句中要用虚拟语气，同时我们要注意在这些动词的同根名词后的表语从句或同位语从句中也要使用虚拟语气。例如： But for the help of my English teacher, I the first prize in the English Writing Competition. A. would not win B. would not have won C. would win D. would have won 【答案】B【解析】考查虚拟语气。此处虚拟语气表示与过去事实相反，句子谓语动词用would/should/could/might + have done结构，故选B。情态动词+have+过去分词的用法情态动词+have+过去分词”成为情态动词语法项目中考查的热点。【例题1】一The door was open一It openI had locked it myself and the key was in my pocketAcannot be Bmust not be Ccannot have been Dmust not have been【解题指导】1must+have+过去分词：表示对过去发生的动作或存在的状态进行推测。只用于肯定句中，意思是”一定已经”。2maymight+have+过去分词：表示对过去发生的动作或存在的状态进行不肯定的推测，可用于肯定句和否定句。might+have+过去分词还可用于虚拟语气，表示过去本来要做某事却未做。3cancould+have+过去分词：常用于否定句(意思是”不可能已经”)和疑问句；could+have+过去分词除用于否定句及疑问句表推测外，还可用于虚拟语气。4neednt+have+过去分词：表示过去做了不必做或不需要做的事情，含有”本来不必”之意。5shouldought to+have+过去分词：肯定式表示”过去本应做某事(但没做)”；否定式表示”过去本来不该做某事(但做了)”。该句式含有不满或责备之意。因此，考生解题时要把握好两点：1是推测还是虚拟；2用于肯定句、疑问句，还是否定句。【解析】C。根据后文“I had locked it myself and the key was in my pocket”可以判断出，空白处是对过去情况的推测：门不可能是开着的。因此用cannot have been。【例题2】You in persona letter would llave been doneAneednt come Bdid not need to have come Cdont have to come Dneednt have come【解题指导】would+have+过去分词：用于虚拟语气，表示过去本来要做某事却未做。弄清此结构是解题的关键。【解析】D。后面的”would+have+过去分词”构成虚拟语气，表示过去本来可以做但是没有做的事实际上没有写信，而是亲自来了，由此可以推出空白处的意思是：你本来不必亲自来的。表达本来不必做但却做了用”neednt+have+过去分词”，故答案为D。高频情态动词should，can，must等的用法近三年全国各地区考查should的用法的题目有6道，是高考考查的热点之一。【例题3】There be any difficulty about winning the speech contest now that you are well prepared for itAmustnt Bmust Cshouldnt Dneedntlira【解题指导】对于should，不仅要掌握其”应该”的意思，还要掌握它的其他用法，如should表示推测的用法、用于虚拟语气的用法和表示”惊奇”的语气。【解析】C。此题考查should表示推测的用法。“now that you are well preparedfor it”是推测的根据：既然你已经作好了充分的准备，那么在演讲比赛中胜出就不应该有什么困难。因此答案为C。【例题4】一could I use your computer to send an email?一Yes-of course you Amight Bcould Ccan Dshould【解题指导】常见的情态动词的用法也是高考考查情态动词的热点之一。要想做好该类题目，首先要掌握这些情态动词的基本用法，然后在做题时根据具体的语境确定正确的答案。【解析】C。问句“Could I use your computer to send an email?”是在征求对方的准许，其中的could并不是指过去，而是表示委婉语气。答语”Yes”表明是给予准许，故用can表示许可。【例题5】一Here is your book，madam一There be a mistakeI have never ordered a book from this shopAmay Bcan Cmust Dshould【解题指导】must的意思取决于它用于肯定句还是否定句，must在肯定句中表”必须，一定”(表示义务、意图或建议)。must还可以表示”偏要”(表示与说话人愿望相反)。解题时要结合语境进行判断。【解析】C。根据“I have never ordered a book from this shop”可以推出，前一句应是表达”肯定是出错了”。因此答案为C。【例题6】一May I have a smoke here?一No， you ，because there are children here。Aneednt Bmustnt Cwont Ddont have to【解题指导】must在否定句中表”不许”。【解析】B。问句“May I have a smoke here?”是在征求对方的准许。结合答语“No”可以判断出，此处应是表达”不允许”之意。因此用mustnt。虚拟语气的用法【例题7】The housemaster was strictHe requested that we television onweeknightsAnot watch Bmust not to watch Cnot be watching Dhave not watched【解题指导】1“should+动词原形”型虚拟语气：(1)在suggest，demand，in-sist，ask等表示建议、命令、请求的动词后的宾语从句中，从句的谓语用”(should+)动词原形”；(2)在表示建议、要求、命令等的名词advice，idea，order，demand等后面的表语从句和同位语从句中，谓语动词用”(should+)动词原形”。2虚拟语气在wish后的宾语从句中的用法。动词wish后接宾语从句时，从句谓语要用虚拟语气。若表示与现在事实相反的愿望，从句谓语用一般过去时；若表示与过去事实相反的愿望，从句谓语用过去完成时；若表示将来没有把握或不太可能实现的愿望，用”wouldcould+动词原形”。【解析】A。request的意思是”要求”，其后的宾语从句要用虚拟语气，谓语动词用”(should+)动词原形”，故答案为A。【例题8】He was so busy doing his experiments in physics，otherwise he you much helpAwould have given Bwould give Cwill give Dgave【解题指导】本题的解题关键是弄清含蓄型虚拟语气的用法。含蓄型虚拟语气，即当用but for，without等词(短语)来代替条件状语从句或者用otherwise等表示与上下文所指的情况不同时，要用虚拟语气。【解析】A。这是一个含蓄型的虚拟语气。句中用otherwise表示与上文所指的情况不同，因而应用虚拟语气。otherwise在此句中相当于“if he had not been so busy doing his experiments in physics”，故答案为A。【例题9】If she harder，she would have succeededAworked Bwork Chad worked Dwould work【解题指导】虚拟语气在条件状语从句中的用法：1表示与现在事实相反的假设，条件状语从句中的谓语动词用“过去式(be动词的过去式用were)”，而主句中的谓语动词用“wouldshouldcouldmight+动词原形”。2表示与过去事实相反的假设，条件状语从句中的谓语动词用过去完成时，主句中的谓语动词则用“wouldshouldmightcould+have+过去分词”。3表示与将来事实相反的假设，条件状语从句中的谓语动词用一般过去时或“should(were t0)+动词原形”，而主句中的谓语动词则用“wouldshouldcouldmight+动词原形”。4当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，动词的形式要根据它所表示的时间作相应的调整。【解析】C。此题考查条件状语从句中的虚拟语气。根据主句的谓语“would have succeeded”可知，此处表示与过去事实相反，因此条件从句用过去完成时。三、【考点在线】虚拟语气考点透析 考点一、虚拟语气的基本用法 1.与现在事实相反的虚拟语气，基本结构为：主语+动词的一般过去时（be动词用were）+其他成分+if+should/would/could.+动词原形+其他成分。例如： If it were not for the fact that she _ sing，I would invite her to the party. A.couldnt B.shouldnt C.cant D.might not 解析 句意为：如果不是因为她不会唱歌的事实，我会邀请她来参加那次聚会的。that从句为同位语从句，描述的是事实，用陈述语气。正确答案为C。 2.与过去事实相反的虚拟语气，基本结构为：主语+动词的过去完成时+其他成分+if+should/would/could.+have done+其他成分。例如： If the weather had been better，we could have had a picnic.But it _ all day. A.rained B.rains C.has rained D.is raining 解析 句意为：如果天气好的话，我们是能够去野餐的，但是下了一天的雨。句子前半部分陈述的是与过去事实相反的事情，所以用了虚拟语气。“下了一天的雨”是事实，所以用陈述语气。因为是发生在过去的事实，所以正确答案为A。 3.与将来事实相反的虚拟语气，基本结构为：主语+动词的一般过去时/should do/were to do+其他成分+if+should/would/could.+动词原形+其他成分。例如： If I _ plan to do anything I want to，Id like to go to Tibet and travel through as much of it as possible. A.would B.could C.had to D.ought to 解析 句意为：如果我能够计划做我想做的事情，我想去西藏并且尽可能多玩一些地方。句子描述的是与将来事实相反的事情，所以正确答案为B。 考点二、含蓄虚拟条件句 这样的虚拟句不含有if从句，而是以but for/without/or/otherwise等引导的句子代替if从句，主句的谓语动词的形式与前面虚拟语气的基本用法相同。例如： Thank you for all your hard work last week.I dont think we _ it without you. A.can manage B.could have managed C.could managed D.can have managed 解析 由语境可知这里要表达的意思是：如果没有你们辛勤的工作，我们不可能处理好这件事。很显然，这是对过去发生的事实的虚拟，所以要用could have done，故应选B。 考点三、主从句时间不一致的虚拟条件句 在有些虚拟条件句中，主从句时间不一致，应根据不同情况区别对待。例如： Its hard for me to imagine what I would be doing today if I _ in love，at the age of seven，with the Melinda Cox Library in my hometown. A.wouldnt have fallen B.had not fallen C.should fall D.were to fall 解析 句意为：如果不是我在七岁时爱上家乡的Melinda Cox图书馆的话，很难想象今天的我会是什么样子。主句描述的是与现在事实相反的事情，从句描述的是与过去事实相反的事情。正确答案为B。 考点四、名词性从句中的虚拟语气 在含有表示坚持、建议、命令、要求等含义的名词性从句和在it做形式宾语或形式主语的复合句中，宾语补足语是necessary/strange/essential/natural/a pity/a shame等表示“惊奇、惋惜或者理应如此”等含义时，从句中的谓语动词需用“should+动词原形”，其中should可以省略。例如： Dont you think it necessary that he _ to Miami but to New York？ I agree，but the problem is _ he has refused to. A.will not be sent；that B.not be sent；that C.should not be sent；what D.should not send；what 解析 问句句意为：难道你不认为必须把他送到迈阿密而不是纽约吗？句子表示理应如此的意思。正确答案为B。 考点五、wish/if only/would rather从句中的虚拟语气 具体说来其基本结构为：wish/if only/would rather+主语+动词一般过去时（表示与现在事实相反，其中be动词用were）/动词过去完成时（表示与过去事实相反）/would+动词原型（表示与将来事实相反）。例如： Look at the trouble Im in，if only I _ your advice！ A.followed B.would follow C.had followed D.should follow 解析 句意为：看我目前的困境，要是我听你的建议就好了。其描述的是与过去事实相反的事情。正确答案为C。 情态动词考点透析考点一、情态动词基本含义的考查 情态动词的基本含义，一直是高考考查的重要内容。例如： 1. The fire spread through the hotel very quickly but everyone_get out. A. had to B. would C. was able to D. could 【解析】考查情态动词的基本含义。had to：不得不； would：表示意愿或过去常常；could倾向于表示经过长期训练而获得的能力；was able to 表示经过努力而能够做到的事或成功地做了某事。因此，答案是C。 2. When can I come for the photos? I need them tomorrow afternoon. They_be ready by 12:00. A. can B. should C. might D. need 【解析】can：能够；should:应该，表示责任、义务。Might：可能；need：需要。它们应该在12点前准备好。所以，答案是B。 3. You cant imagine that a well-behaved gentleman_be so rude to a lady . A. might B. need C. shouldD. would 【解析】should 表示说话人感情，如惊奇、愤怒、失望等。在此句中表示说话人一种惊奇的语气。 句意为：你不可能想象出体面的绅士竟然对一位女士那么粗鲁。答案是 C。 分析：高考对情态动词基本含义的考查，仍然集中在常用的情态动词上。对常用情态动词的含义，要掌握的既准确又要全面，特别是shall, should, can, may 四个常用情态动词的含义较多，不易理解，复习时应当引起重视。二、情态动词表示推测的考查 对情态动词表示推测的用法，是高考考查情态动词的一个重要方面。例如： 1. Sorry, Im late. I_have turned off the alarm clock and gone back to sleep again . A. might B. should C. can D. will 【解析】might have done : (过去)可能做过某事；shouldhave done :本应该做某事。根据本句提供的情境Im late 表明说话人可能把闹钟关上了。答案是：A。 2. My sister met him at the Grand Theatre yesterday afternoon,so he_your lecture. A. couldnt have attended B. neednt have attended C. mustnt have attended D. shouldnt have attended 【解析】couldnt have done: (过去)不可能做某事； neednt have done:本来不必做某事；mustnt have done:一定未做过某事： shouldnt have done:本不该做某事。根据提供的情境My sister met him at the Great Theatre表明他不可能参加讲座。答案是：A。 3.Mr Bush is on time for everything. How_it be that he was late for the opening ceremony? A. can B. should C. may D. must 【解析】can表示可能性。布什先生按时做一切事，他怎么可能开幕式迟到呢？答案是：A。 4.I heard they went skiing in the mountains last winter? It_true because there was little snow there. A. may not be B. wont be C. couldnt be D. mustnt be 【解析】may not be : 可能不是；wont be：不会是；couldnt be：不可能是； mustnt be ：一定不是。根据提供情境there was little snow 说明山里滑雪是件不可能的事，may not 语气不如couldnt强。答案是：C。 分析：高考对表示推测的情态动词集中在must, can, could, may, might上，准确掌握它们使用的场合，是解决问题的关键。Must 用于肯定陈述句，表示肯定推测；can, could用于疑问或否定陈述句，表示可能性推测；may, might用于陈述句，表示可能性推测；用于否定陈述句中，cant （不可能）的语气比may not（可能不）强。此外，还要注意有对过去和对现在两种情况的推测,对过去推测用情态动词+have done ，对现在推测用情态动词+ 动词原形。 三、情态动词表示虚拟的考查 情态动词have+过去分词表示与过去事实上相反的情况，也是高考单项选择题涉及到情态动词的一个重要方面。 1. There was a lot of fun at yesterdays party. You_come, but why didnt you? A. must have B. should C. need have D. ought to have 【解析】ought to have done 表示本来应该做某事而实际没做，should do 表示现在应该做某事，与题中 at yesterdays party 表示的时间不一致。所以选D。 2.I was really anxious about you. You_home without a word.(NMET2001,33)A. mustnt leave B. shouldnt have left C. couldnt have left D. neednt leave 【解析】shouldnt have done 表示本来不应该做而实际上做了。句意为：你不应该不说一句话就离开家，而实际上是没说一句话就离开家了。答案是：B。 3.Oh, Im not feeling well in the stomach. I_so much fried chicken just now. A. shouldnt eat B. mustnt have eaten C. shouldnt have eaten D. mustnt eat 【解析】该句所表达的意思是刚才我不因该吃那么多炸鸡，而实际上是吃了那么多，可以判断用shouldnt have eaten. 答案是 C。 分析：高考对情态动词表示虚拟用法，表示与过去事实相反的情况。近几年高考，主要侧重should （not）have done 这一句式上，表示本来不该做却做了或本来该做却未做的事，在复习时，还应关注其它几种虚拟形式，如need (not)have done 表示本来需要做而未做或本来不需要而做的事等等，以做到有备无患。 考点四、情态动词与助动词混合考查1.Tom ,you didnt come to the party last night? I_, but I suddenly remembered I had homework to do .(NMET2007全国卷II，20) A. had to B. didnt C. was going to D. wouldnt 【解析】had to:不得不；didnt:没来；was going to：打算来；wouldnt:不愿来。句意：汤姆，昨晚你没来参加舞会吗？我本打算来，但我突然记起有作业要做。But是关键词，所以答案是：C。 2.Your phone number again? I_quite catch it . Its 86184867. A. didnt B. couldnt C. dont D. cant 【解析】记住电话号码并非难事，未完全听清楚电话号码并非能力的事，此处只是说没有完全听清楚电话号码，所以，应选A。四、【易错点睛】易错角度 1 情态动词的词汇义辨析1.Helen _ go on the trip with us, but she isnt quite sure yet.A. shall B. must C. may D. can【错解】 D【纠错心得】 这里表示“能够”的can。根据后文“她还不是很肯定”，那么应当是不肯定的语气may了。【答案】 C2 I often see lights in that empty house. Do you think I _ report it to the police?.A. should B. may C. will D. can【错解】 D【纠错心得】 本题的解题思路要从情态动词本身的意义和用法开始。按照情景，在空房子里看到灯光，是一件奇怪而令人生疑的事，所以会问:你是否认为我应当把这事情报告给警察?强调“应该”，所以用should.【答案】 A易错角度 2 情态动词对话情景中的用法1.Lucy doesnt mind lending you her dictionary.She .Ive already borrowed one.A. musnt B. may not C. cant D. neednt【错解】 A【纠错心得】 前句是说“Lacy不介意把字典借给你用”，后者说“我已经借了一本”，所以是没有必要了，填 neednt符合语境。【答案】 C2.I dont mind telling you what I know.You. Im not asking you for it.A. mustnt B. may not C. cant D. neednt【错解】 A【纠错心得】 前句话说:我不介意告诉你我所知道的事情。后句说:你没有必要告诉我，我并没有向你问此事:、因此，是没有必要neednt，而不是禁止的mustnt.【答案】 D易错角度 3 情态动词+have+过去分词结构1.The woman biologist stayed in Africa studying wild animals for 13 years before she returned.Oh, dear ! She _ a lot of difficulties !A. may go through B. might go throughC. ought to have gone through D. must have zone through【错解】 C或A【纠错心得】 按照语境是对过去可能发生事情的一种猜测，而表示现在的事情。选项C表示“应该做的事情而没有做”的责备。【答案】 D2.I 11 tell Mary about her new job tomorrow.You her last week.A. ought to tell B. would have told C. must tell D. should have told【错解】 B或A【纠错心得】 句意为:你上个星期就应该告诉她的。表示对过去应该做的事情但没有做的一种责备，那么只有D项符合了。【答案】 D3.I stayed at a hotel while in New York.Oh,did you? You with Barbara.A. could have stayed B. could stay C. would stay D. must have stayed考场易错 D【纠错心得】 题干中did you这个信息说明了是一个表示疑问语气的句子，而D项是表示对过去事实的肯定推测，所以是错误的。could have done表示“应该(可以)做的但是没有做”，符合语境。【答案】 A易错角度 4 虚拟语气的一些特殊句式1. If I _ plan to do anything I wanted to do, Id like to go Tibet and travel through as much of if as possible.A. would B. could C. had to D. ought to【错解】 A【纠错心得】 受if条件虚拟语气的影响，会误选A，根据句意，如果“能够的话”，当用could更符合语境。【答案】 B2.You didnt let me drive. If we_turn, you so tired.A. drove; didnt get B. drove; wouldnt get C. were driving; wouldnt get D. had driven; wonldnt have got【错解】 A【纠错心得】 主句、从句两个部分都表示与过去事实相反。【答案】 D专家会诊虚拟语气中的几种特殊情况1.if省略句在条件句中，可省略if把were，had，should提到句首，变为倒装句式。如果谓语动词是否定形式时，不能用动词的缩略形式。例如:Should it (If it should) rain tomorrow; we would not go fishing.Were it not (if it were not)the expense, I would go abroad now. (不能用 werent)2.在would rather后的宾语从句中的虚拟语气形式用动词的过去式，在It is(hish) time (that)句型中，从句中的谓语动词用过去式，或 should + 动词原形，但should不能省略。例如:It is high time that you went to school.It is high time we should start out.I would rather they didnt hear of the news.3.在口语中，虚拟语气的省略情况口语中，虚拟语气的省略情况要注意。如果是一般过去时，只保留did，could，were等助动词、情态动词或系动词如果是过去完成时，要保留had；如果是过去将来时，要保留wouldmight.同时还要注意被动情况。例如:Have you found the answer to the question?I wish I had( found the answer to the question).I cant go to Beijing with you, but I wish I would (go to Beijing with you).Have you finished your homework?I would have ( finished my homework) if I had not gone to the cinema last night.The liitle boy who dark the poison by mistake died if he had been sent to the hospital earlier.Well. he should have been (sent to the hospital earlier).4.if only和 only if 句型(1) if only可以用来表示对现在或未来的愿望,也可以表示与过去事实相反的愿望。例如:If only I could swim.(现在的愿望)If only they would tell me what they have decided. (将来的愿望)If only they had remembered to buy some fruit just now. (与过去事实相反的愿望)(2)only if用于句首，后接从句主谓倒装，意思是“只要，只有”。例如:Only if the red light comes on is there any danger to employees.Only if a teacher has given permissionis a student allowed to enter this room.五、【高考母题】（2010高考英语江苏卷）George is going to talk about the geography of his country, but Id rather he_ more on its culture.A.focus B.focused C.would focus D.had focused【解析】本题考察虚拟语气的用法。would rather后应用虚拟语气，表示与现在时间相反，用动词的过去式。【答案】B（2010高考英语上海卷）-Sorry, Professor Smith. I didnt finish the assignment yesterday.-Oh, you have done it as yesterday was the deadline.A. must B. mustnt C. should D. shouldnt【解析】本题考查的是虚拟语气。此处表示和过去事实相反的情况，应该用should + have + 过去分词。本来应该做，而未做 【答案】C（2010高考英语浙江卷）Had I known about this computer program, a huge amount of time and energy .Awould have been savedBhad been saved Cwill be saved Dwas saved【解析】 本题考查虚拟语气。根据句子的倒装特征判断此处是省略了if的虚拟语气，原形是：If I had known about this computer program, a huge amount of time and energy .故选择A。句意为：如果我早知道这个电脑程序，就可以节省大量的时间和精力了。【答案】 A（2010高考英语天津卷）John went to the hospital alone. If he me about it, I would have gone with him.A. should tell B. tells C. told D. had told 【解析】考察虚拟语气。句意为“约翰自己去医院了。如果他告诉我这件事情，我就会和他一起去去医院。根据句意可知主从句都是对过去发生事实的一种意愿表达，采用虚拟语气，所以从句采用have done的结构，故选D。（2010高考英语陕西卷）If we _ the other road, we might have arrived here in time for the meeting. A. take B. had taken C. took D. have taken【解析】考查虚拟语气。所填词做虚拟语气中条件状语从句的谓语，根据主句的谓语动词形式might have arrived可知题干是与过去事实相反，故所填部分用had+过去分词形式，选B。（2010高考英语湖南卷）If he my advice, he wouldnt have lost his job. A. followed B. should follow C. had followed D. would follow【解析】考查虚拟语气。根据“wouldnt have lost”可判断if引导的状语从句表示与过去事实相反的虚拟，故选C项。（2010高考英语北京卷）-The weather has been very hot and dry.-Yes. If it had rained even a drop, things would be much better now! And my vegetables . A. wouldnt die B. didnt die C. hadnt died D. wouldnt have died【解析】考察虚拟语气。句意为：“天气是又热又干燥。”“是的。如果下雨就算是一滴的话，现在也许就会好很多！我的蔬菜也就不会干死了。”由句意可知此处是一种虚拟，表示与过去事实相反的假设，故主句用would/could/might/should+have done，即D项正确。（2010高考英语江苏卷）-I havent got the reference book yet, but Ill have a test on the subject next month. -Dont worry. You_ have it by Friday.A. could B. shall C. must D. may 【解析】本题考察情态动词的用法。shall在第二人称中表示允诺，还可表示强制，命令，威胁，警告等，还有在法律条文中的要求和规定。【答案】B（2010高考英语上海春季卷）It is important to know about the cultural differences that cause problems.Amust Bdare Cneed Dmay【解析】情态动词。语意：了解一些可能会引起问题的文化差异，这很重要。此处may用来表示可能；must，一定，必须；dare作情态动词常用在否定句与疑问句中，表示敢于；need表示必须，需要。根