高中生物 第7章 第2节 现代生物进化理论的主要内容课件 新人教版必修2 (67)

1、情态动词的基本用法1.shall(1) 用在第一、三人称的疑问句中，表示征求对方的意见或指示。 Has Mr.Wang arrived?王先生到了吗？Yes， already. Shall he wait outside or just come in?是的，已经到了。是让他进来，还是在外面等？(2) 用于第二、三人称陈述句中，表示命令、许诺、警告、强制、威胁、决心等。 The school rules state that no child shall be allowed out of the school unless accompanied by an adult.学校制度规定，除非有

2、家长陪伴，任何孩子不准离开学校。2.must(1)表示禁止(用于否定句)。 Smoking must not be allowed in the office.严禁在办公室吸烟。(2)表示偏执、固执，常译成“一定要，非要”。 Why must you be talking so loudly while others are studying?为什么在别人正学习的时候，你非得这么大声说话呢？ (2011大纲全国卷) If you must smoke, please go outside.如果你一定要吸烟，请到外面去。3.should(1)表示根据经验常识预测可能性，并意为“可能，(按道理)应

3、该”。 Its nearly 7 oclock. Jack should be here at the moment.快7点了，杰克此刻应该在这儿了。(2)竟然，居然 I am surprised that you should speak in such a way.我很惊奇你居然用那种口气说话。4.would 与used towould 可表示过去反复发生的动作或某种倾向，后面接表示动作的动词，不能接表示状态的词。used to表示过去的习惯动作或状态，强调现在已不存在。 He would come to see us on Sundays.过去他经常星期天来看望我们。 Our compa

4、ny used to do business with theirs.过去我们公司和他们的公司常有业务往来。5.can 和could 的用法(1)表示惊讶，常用在否定句和疑问句中。 How could you do such a silly thing?你怎么能做那样的蠢事呢？(2)cannot.too/enough 表示“无论也不过分”，“越越好”。 You cant be too careful while driving.开车时越小心越好。6.“may as well动词原形”意为“最好，不妨，倒不如”。 You may as well do it at once.你最好马上就做这件事。

5、 We may as well stay where we are.我们留在现在的地方倒也不错。1.“must/may/might/cant/couldnt+动词原形”对现在发生的动作或存在的状态的推测。“must/may/might/cant/couldnt+be doing” 对正在进行的动作的推测。“must/may/might/cant/couldnt+have done”对过去或已经完成的动作的推测。 He couldnt be doing his homework, because there is a wonderful football match now.他不可能在做家庭作业

6、，因为现在有场精彩的足球比赛。 You must have said something to upset him.你一定说了什么让他不高兴的话。情态动词表“推测”2.can 用于肯定句中有时可以用来表示推测，意为“有时会”；用于疑问句中可以表示推测，意为“可能”，有时表示一种惊讶的语气；用于否定句中也可以表示推测，cant 意为“不可能”，语气很强烈。 Mr.Bush is on time for everything. How can it be that he was late for the meeting?布什先生做什么事情都很准时，他怎么可能开会迟到呢？ It is usually

7、 warm in my hometown in March， but it can be rather cold sometimes.我的家乡通常在三月份很暖和，但有时会相当冷。3.may， might用于肯定句中可以用来表示推测，意为“可能”；用于否定句中也可以表示推测， may not 意为“可能不”，表示一种不太确定的语气。 The traffic is heavy these days. I might arrive a bit late， so could you save me a place?最近这些天交通拥挤，我有可能迟到一会儿，因此请你给我留个位子好吗？ Liza may w

8、ell not want to go on the tripshe hates travelling.莉莎可能不想去旅行，她厌恶旅行。（may 常与well连用，may well 主要用于加强推测语气，表示有较大的可能性。）4.must 表示推测时只能用于肯定句中，意为“一定，必定”，表示十分肯定的(在疑问句中或否定句中要用can)。 Hi， Tom. Any idea where Jane is?嗨，汤姆，你知道简在哪儿吗？She must be in the classroom. I saw her there just now.她肯定在教室里，我刚才在那儿看到她了。5.should 用来

9、表示推测时意为“应该”，即含有“按道理来说应当如此”的意思。 The public transport in Beijing is very convenient， so there shouldnt be any difficulty in traveling around the city.现在北京的公共交通非常便利，所以在市区观光不应该有什么困难。情态动词+have done1.could have done用于肯定句，表示本来可以做，而实际上未做，用疑问或否定形式对过去发生的行为表示推测，cant have done 多用于语气强烈的否定，意为“不可能做过”。 The accident

10、 could have been avoided.这场事故本来是可以避免的。2.may/might have done 表示对过去行为的推测，意为“可能做过”。might 所表示的可能性比较弱，语气较委婉。此外might have done 可表示“本可能做而实际上未做”。 I cant find my purse anywhere.我到处都找不到我的钱包。You may have lost it while shopping.你可能在购物的时候弄丢了。 3.must have done 表示对过去行为的推测，意为“一定，想必”，语气十分肯定。 It must have rained last

11、 night, for the ground is wet. 昨晚肯定下雨了，因为地面是湿的。4.should/ought to have done 用于肯定句时，表示“过去本该做某事，而实际上未做”；shouldnt have done/oughtnt to have done则表示“过去不该做某事反而做了”。 Im not feeling well in the stomach. I shouldnt have eaten so much fried chicken just now.我现在觉得肚子疼，我刚才不应该吃那么多的炸鸡。5.neednt have done 表示“本来不必做某事而

12、实际上却做了”。 I actually neednt have bought so much wineonly three people came. 其实我本没必要买这么多酒，只来了三个人。非真实条件句的虚拟语气情况情况从句的动词从句的动词主句的动词主句的动词 例句例句与现在事实相反动词的过去式(be动词一律用were)would/could/should/might 动词原形 If I had time， I would attend your party.如果我有时间，我就去参加你的宴会了。 If I saw him now， I would be very happy.如果我现在见到他，

13、我会很高兴的。与过去事实相反had过去分词would/could/should/mighthave过去分词 You didnt let me drive. If we had driven in turn， you wouldnt have got so tired.你当时不让我开车。如果我们轮流开，你就不会觉得那么累了。与将来事实相反动词的过去式;should动词原形；were to动词原形would/could/might/should动词原形 If it snowed/were to snow/should snow tomorrow， we would take photos.如果明天

14、下雪，我们就照相。注意注意：(1)若条件句中有were， had， should，可把if 省略，而把were， had， should 放在主语前，形成倒装结构，这种结构主要用于书面语中。 Were I you, I would stay.倘若我是你，我就留下。 Should I be free tomorrow, I would come.如果我明天有空，我会来。 Had you taken my advice， you wouldnt have failed in the examination.如果你听了我的建议，你就不会考试不及格了。(2)有时主句和虚拟条件从句的动作发生的时间不一致

15、，此时，主句和从句的谓语动词要根据各自所指的不同时间选择适当的动词形式。 If you had worked hard， you would be sitting comfortably in an office now.如果你真的努力工作了，你现在就会舒适地坐在办公室里。(从句指过去，主句指现在)(3)有时虚拟条件并不通过条件从句表达出来，而是通过词、短语或上下文暗示，此时句子的时态要依具体情况而定。 Without electricity (If there were no electricity)， life would be quite different today.如果没有电，今天

16、的生活就会完全不同。 But for your help， it would have caused a serious loss.要不是你的帮助，那将会导致巨大的损失。 I was busy that day. Otherwise I would have gone there with them. (If I hadnt been busy that day， I would have gone there with them.)我那天很忙，否则，我就和他们一起去那儿了。1.在表示建议、命令、要求、愿望等的词相关的名词性从句中用虚拟语气，形式为：(should)动词原形。常这样用的动词有：

17、suggest 建议； advise 劝告； propose建议； recommend 推荐，劝告，建议； demand 要求； desire 渴望； insist 坚持，坚决要求； prefer 宁愿； urge 主张； request 要求； require 要求； order 命令， command 命令，以及这些词的名词形式。 Mr.Johnson insisted that the problem worthy of attention (should) be discussed at the meeting.约翰逊先生坚决要求应在会议上谈论值得注意的问题。 My advice is

18、 that we should think it over before accepting it. 我的建议是在接受之前要认真考虑。名词性从句中的虚拟语气注意：注意：suggest作“表明，暗示”讲时，其从句不虚拟。即： 物+suggest(表明，暗示)+that 从句（不虚拟） 人+suggest（建议）+that 从句（要虚拟，用should+动 词原形） Janes pale face suggested that she was ill， and her parents suggested that she (should) have a medical examination.简苍

19、白的脸色表明她生病了，她父母建议她做一下健康检查。insist作“坚持，坚决要求”讲，其从句要虚拟（should+动词原形）；insist作“坚持说，坚持认为”讲，其从句不虚拟。 The young man insisted that he didnt steal the money. 那个年轻人坚持说他没有偷钱。2. wish后面所跟宾语从句中的虚拟语气 表示对现在情况的虚拟：wish主语动词过去式或were 表示对过去情况的虚拟：wish主语had过去分词 表示对将来情况的虚拟：wish主语would动词原形 I wish she were here.她在这儿就好了。 I wish she

20、 had taken my advice.那时她要是听我的话就好了。 I wish you would go with us tomorrow.但愿你明天跟我们一块去。3.主语从句中的虚拟语气在表达惊讶、惋惜、遗憾，理应如此等意义的主语从句中常使用虚拟语气，其虚拟语气的结构为：should+动词原形。主句中的谓语动词形式不限。句型： Its+adj.(如necessary, important, strange, natural, essential, curious等)+that从句（从句中常用should+动词原形） It is suggested/requested/proposed+t

21、hat从句(从句中常用 should+动词原形) Its important that we should learn English well.我们学好英语很重要。 Its suggested that the meeting should be put off till next week.有人建议会议推迟到下星期。其他句型中的虚拟语气1.would rather 句型中的虚拟语气表示愿望，意为“宁愿，但愿”。(现在和将来的愿望用过去时；对过去的愿望用过去完成时) Id rather we didnt go to see a film this evening.我倒希望我们今晚不去看电影。

22、 Id rather you had returned the book yesterday. 但愿你昨天把书还了。2.It is (high/about) time (that).句型中的虚拟语气在句型“It is (high/about) time.”后面也可跟虚拟语气，从句中常用过去式。有时也用“should动词原形”，意为“该是的时候了”。 It is time (that) we went home.我们该回家了。比较比较：Its the first time (that) I have had such a wonderful meal. It was the second tim

23、e (that) you had broken the window.（当time前有序数词时， 后面从句用完成时。）3.if only 引导的感叹句中的虚拟语气在“if only”引导的感叹句中，要求用虚拟语气，表示愿望。用过去时或“would/could动词原形”表示与现在或未来事实相反的愿望；用过去完成时表示与过去事实相反的愿望。 If only I were a bird! 要是我是一只鸟该多好啊！ If only I had not been ill last week!要是上周我没病该多好啊！4. as if/as though 从句中的虚拟语气如果as if/as though引

24、导的从句谓语动词与主句动词所表达的动作同时发生， as if/as though从句中谓语动词用过去时；如果as if/as though引导的从句谓语动词所表达的动作先于主句谓语动词所表达的动作，从句用过去完成时。 When a pencil is put into a glass of water, it looks as if it were broken. 当把铅笔放入一杯水中，它看起来就像是断了。 When Mary met Tom in the street, she pretended as if she hadnt seen him.当玛丽在街上遇到汤姆，她假装没有看见他。5.

25、过去完成时had meant/wanted/intended/planned to do 表示“过去原本打算做，但实际上没做成。” I had meant to help you, but I got caught in the traffic.我本打算帮你，但我堵车了。.单句填空单句填空1.Its eight oclock already. Jack _ be here by now.Oh, he told me that he was going to see his dentist and wouldnt be back until ten.【解析】句意：8点钟了。杰克现在应该到了。哦，

26、他告诉我他要去看牙医，在10点以前是不会回来的。should有“根据情理或常理推断某事将可能发生”之意。【答案】1.should2. Jack, take more clothes when going camping. It _ be very cold in the mountains.Thank you, Mum. I will.【解析】句意：8点钟了。杰克现在应该到了。哦，他告诉我他要去看牙医，在10点以前是不会回来的。should有“根据情理或常理推断某事将可能发生”之意。【答案】2.can3.Our teacher insisted that the key words worth

27、 paying attention to _(underline) before class.【解析】句意：我们老师坚持要在课前将值得注意的关键词划线。insist后的宾语从句中的谓语动词应是should+动词原形，其中，should 可以省略；根据句意应用被动。【答案】3.(should)be underlined4.If Jim _(be) more independent, his parents divorce would not have affected him as deeply. 【解析】句意：如果吉姆当时更加独立一些,他父母离婚就不会如此深深地影响他。考查对已发生之事的虚拟，

28、从句用had done形式，主句用would+have done形式。【答案】4.had been5.If the dog hadnt woken us, we wouldnt have noticed the fire and it _(spread) to the house next door.【解析】句意：如果当时不是这只狗把我们弄醒,我们就不会注意到火，那么大火就可能会蔓延到隔壁的房子。前半句是虚拟，后半句是对过去可能发生之事的推测，因为只是可能性，故用might+have done形式。【答案】 5.might have spread6.It is required that al

29、l traffic participants _(observe) the traffic rules to make traffic safer and faster. 【解析】句意：要求所有交通参与者应遵守交通规则,让交通更安全、更顺畅。require后的从句里的谓语动词应是should+动词原形，其中，should 可以省略。句中that后是真正的主语从句，而句首的it是形式主语。【答案】6.（should） observe7.After supper she _ sit down by the fire, sometimes as long as an hour, thinking o

30、f her young and happy days.【解析】句意：晚饭后她总会在火旁坐下来,有时长达一个小时,想着她那些年轻和快乐的日子。would 有“过去总是”之意，往往是对过去发生的事情的追忆。【答案】7.would8.Most students went to the party yesterday. It is a pity that you were absent.I wish I _(have). But I was terribly busy.【解析】句意：大多数学生去了昨天的聚会，遗憾的是你缺席。我也希望我能参加啊,但我太忙了。wish后的虚拟语气用had done形式，表

31、示对已发生之事的虚拟，这里意为：I wish I had gone to the party yesterday.为了简洁，相同的动词和宾语gone to the party被省略了。【答案】8.had9.The job position in the advertisement requires that the applicant _(have) at least 8 years of working experience.【解析】句意：广告中的职位要求申请人至少有8年的工作经验。主句中有谓语动词require,其后的从句应用should+动词原形，should可以省略。【答案】9.(sh

32、ould) have10.Our parents and teachers often tell us that we _ be careful enough no matter what we do.【解析】句意：我们父母和老师经常告诉我们：无论我们做什么，我们怎么小心也不过分。cannot be+adj./adv.+enough+to do意为“越就越好；怎么也不过分”。【答案】10.cant11.Jack fell off the ladder yesterday, but he is all right now.What a lucky dog! He _(injure) himsel

33、f badly. 【解析】句意：Jack昨天从梯子上摔了下来，但是现在没事了。真幸运！他本可能摔得很严重的。根据 “but he is all right now”可知，本句是一个虚拟语气句；根据yesterday可知，此处是对过去的推测，故用情态动词+have done的形式。【答案】11.could have injured12.If Rose hadnt lost her left leg in the accident last year, she _(sit) in the wheelchair now. 【解析】整个句子属于错综条件句，从句与过去事实相反；根据时间状语now可知，主

34、句与现在事实相反，因此答案为wouldnt sit。【答案】12.wouldnt sit13. It _(can) be the vocabulary that caused you the problem in the exercise because you know a lot of words.【解析】句意：因为你已经掌握了很多单词，所以，引起你练习中出现问题的因素不可能是词汇。Couldnt 是非常肯定的推测。【答案】13.couldnt14.Maybe if I _(study) science, and not literature then, I would be able t

35、o give you more help.【解析】句意：也许如果当时我学习的是理科而不是文科的话，那么我（现在）就可以给你更多的帮助了。根据then一词可以确定此处表示与过去事实相反，故if引导的从句部分用had done。【答案】14.had studied15.Colin failed in his attempt to win a prize in the speech contest. I wish he _(practice) his speaking skills for the coming Creativity English Competition.【解析】根据题干中的wis

36、h可知，其后的宾语从句需要用虚拟语气形式，同时根据coming可知，这是将来的比赛，由此可知，说话者强调希望他现在为即将来临的比赛做准备了， 故用wish sb. did表示对现在情况的虚拟。【答案】15.practiced 16.How did you do in the test? Not so well. I _(do) much better but I misread the directions for Part D.【解析】句意：你考试怎么样？不太好。我本能够做得更好的，但我读错了D部分的说明。对过去的推测，用情态动词+have done。【答案】16.could have do

37、ne17. What would have happened if the thief _(enter) the house, without being noticed?【解析】句意：要是贼进了房子而没被发现，那将会怎样呢？根据题干中 would have happened可知，本句话是对过去发生事情的虚拟，由此可知，if从句谓语动词应用had done的形式。【答案】17.had entered18. I felt surprised that anyone of his intelligence _(fail) such an easy test.【解析】考查情态动词表推测的用法。句意：

38、我感到惊讶，像他这样智力的人居然连如此简单的测试都没有通过。should在这里表示惊讶的态度。【答案】18.should have failed19. It is recommended that you _(book) your accommodation in advance in tourist season, as you may find all the best hotels are not accessible. 【解析】句意：推荐您在旅游季节提前预定住宿，因为您可能会发现所有最好的酒店都无法入住的。recommend、suggest等表建议、要求、命令等的词的从句要用shoul

39、d加动词原形表虚拟语气，should可省。【答案】19.(should) book20. Im as busy as a bee; _ you bother me with so many questions now?【解析】句意：我现在像蜜蜂一样忙碌,你偏偏要拿这么多问题来烦我吗? must 常可用来表示“令人不快的事”，意即“偏偏要”。【答案】20.must21. But for your timely warning, we _(get) into great trouble.Well, you know were friends.【解析】本句包含含蓄条件的虚拟语气，它表示的条件不是通过

40、if条件句表示出来，而是通过介词短语but for （要不是，如果没有）表示出来的；句意：要不是你及时提醒，我就会陷入大麻烦了。嗯！你知道我们是好朋友的。根据句意可知这件事情发生在过去，故主句使用would have done表示对过去情况的虚拟。【答案】21.would have got22. She got stuck in a terrible traffic jam on the highway to Shanghai, or she _(have) dinner with her family now.【解析】句意：她在去上海的高速上遇到了堵车，不然，她现在将正和家人一起吃晚饭。or

41、否则，要不然，指假设的情况，是一种含蓄条件句，根据句意可知，吃晚饭发生在将来，再根据or表虚拟，应该使用过去将来进行时。【答案】22.would be having23. Its a pity that you were late, otherwise you _(see) the film star Rain from Korea. 【解析】句意：很可惜，你迟到了，否则你就会/可能看到来自韩国的电影明星Rain了。根据otherwise可知，此处是含蓄的虚拟语气，根据were可知，此处表示对过去事实的虚拟，主句应用would/could have done的形式。【答案】23.would/c

42、ould have seen24. If he _(listen) to the teacher attentively in the past year, he _(know) the answer to the question now.【解析】 考查混合型虚拟语气。句意：如果在过去的一年里他认真听老师讲课了，那么他现在就能够知道这个问题的答案了。从in the past year 判断前面条件状语从句是对过去进行假设，应该用过去完成时；而后面主句中的now则提示应该是对现在的虚拟，应该用would +动词原形，所以整个句子是混合型的虚拟语气。【答案】24.had listened; wo

43、uld know25. We would rather our daughter _(stay) at home with us, but it is her choice, and she is not a child any longer.【解析】 would rather后面的从句要使用虚拟语气，如果从句表示与现在或将来事实相反，要用一般过去时，如果与过去事实相反，要用过去完成时。句意：我们宁愿我们的女儿待在家里，但是这是她的选择，她已经不再是孩子了。根据句意可知是与现在事实相反，所以用一般过去时。【答案】25.stayed26. I still remember my happy ch

44、ildhood when my mother _(take) me to Disneyland at weekends.【解析】本句中的would表过去的习惯性动作，可译为“过去常常”，现在可能还会继续做下去。区别于used to do过去常常做某事，通常表示现在已经不这样做了。句意：我仍然记得我那幸福的童年，在那时我的母亲常常在周末带我去迪斯尼乐园。【答案】26.would take27.Should it rain tomorrow, we _(cancel) the football match.【解析】句意：如果明天下雨，我们就取消足球比赛。根据从句的should it可知这是和将来事

45、实相反的虚拟条件句，故主句用would do的形式。【答案】27.would cancel28. To my surprise, some of my students _ stay up to study for the coming examination.【解析】句意：令我惊奇的是,我的一些学生为了即将到来的考试居然要熬夜学习。should可用来表示“惊讶的语气”，意即“居然会，竟然会”。【答案】28.should29. It was John who broke the window. Why are you talking to me as if I _(do) it?【解析】连词短

46、语as if似乎，好像,其后面的从句有两种情况，如果是真的事情，就使用陈述语气；如果表示的是假的事情，就使用虚拟语气。其中与过去事实相反，使用过去完成时；与将来事实相反，使用过去将来时；与现在事实相反，使用一般过去时。句意：打破窗户的是John，为什么你和我说话时就好像是我打破了窗户一样。根据前一句中的was可知打破窗户是过去发生的事情，所以是与过去事实相反的虚拟语气，故使用过去完成时。【答案】29.had done30. You failed to pass the English test again, didnt you? Yeah, if only I _(work) harder a

47、t school!【解析】句意：你的英语考试又没有通过，是吗？是的。我要是在学校更努力些就好了。根据句意可知，此处是对过去情况的虚拟，if only结构中应用had done的形式。 【答案】30.had worked .单句改错1.Mary, now you have a chance to study in Singapore for a year as an exchange student. Are you interested?【解析】句意：玛丽,现在你有机会作为交换生到新加坡学习一年。你感兴趣吗?这是真的吗?我当然会去。may用在问句中表示“许可”；can用在问句中表示“可能性”。

48、【答案】1.MayCanMay that be true? Of course Ill go.2.Whenever we met, Lily could greet me first though I was younger than her.【解析】句意：每当我们见面,莉莉会先问候我，虽然我比她小。would 有“过去总是”之意，往往是对过去发生的事情的追忆。【答案】2.couldwould3.According to the school rules, no student will go out of the school after eleven oclock p.m.【解析】句意：根

49、据校规,学生不得在晚上11点钟后到校外去。shall 用于第二或第三人称的肯定句中时，可表示“规定，命令”等。【答案】3.willshall4.He chose to teach in a western province, though he would have stayed in the city for a better life.【解析】句意：虽然他可以在这个城市过更好的生活，但他却选择到西部省份支教。could have done意为“本能够做(但未做)”。【答案】4.wouldcould5.There is a possibility that these hens could

50、be frightened and lay fewer eggs would there be a sudden loud noise.【解析】句意：如果突然有很大的噪音，这些母鸡有可能会因受到惊吓而少下蛋。在if引导的虚拟句中，如果从句里有should, were 或had这三个动词，可将if省略，主谓倒装，因此，题干的后半句可以看作是：if there should be a sudden loud noise。【答案】5.wouldshould6.Would it have been the failure to pick up directions from the ground co

51、ntrol that caused the air crash?【解析】句意：此次空难是不是因为飞机无法接收地面控制中心的指令造成的？could have done用于疑问句中，可表对已发生之事的推测。【答案】6.wouldcould7.I am worn out now. I stayed up last night to finish the report.Oh? You wouldnt have. The professor asked us to hand it in next week.【解析】句意：我现在疲惫不堪，为了完成报告我昨晚熬夜了。哦?你没有必要这样做，教授要求我们下周交。

52、Neednt have done意为“本没有必要做(但做了)”。【答案】7.wouldntneednt8.Ive told Nancy many times about the meeting, but she still forgot it!I understand. Actually, anyone must be very forgetful at times.【解析】句意：我多次告诉南希关于会议的事情,但她还是忘了!我了解。事实上,任何人偶尔都会健忘。can可用来表示客观可能性。【答案】8.mustcan9.I had thought he would be nervous in th

53、is speech competition, but he turned out to be calm. He should have done quite enough preparation for it. 【解析】句意：我原以为他在这场演讲比赛中会紧张，但他很冷静。他一定是做了足够的准备。must+have done是表示对已发生之事语气很肯定的推测；should+have done 表示“过去应该做（但未做）”。【答案】9.shouldmust10.I wonder if I can board the plane with this return ticket.There shall

54、 be no problem. Your ticket is valid until the end of this month.【解析】句意：我想知道我是否可以用这张回程机票登机。应该没有问题。你的票直到这个月底都是有效的。should 可用来表示“根据情理或常理来判断将会发生的事情”。【答案】10.shallshould11.The basketball team has been doing well this season, so they could win the championship.【解析】句意：本赛季篮球队已经做得很好,所以他们应该会赢得冠军。should有“根据情理或根

55、据常理来判断某事应发生”之意。【答案】11.couldshould12.It is hard to say what kind of person he is. Sometimes he is very friendly; at other times he must be very cold.【解析】句意：很难说他是什么样的人；有时他很友好,有时他很冷淡。 can常可用来表示 “客观可能性”。【答案】12.mustcan13.Take the lift to the eighth floor and turn right. You neednt have any trouble findin

56、g my office.【解析】句意：坐电梯到八楼，然后右转，你找到我的办公室不应该有什么困难。should可用来表示“根据情理某事应该”,同样，shouldnt可表示“根据情理某事不应该”。【答案】13.needntshouldnt14.The house was in such a messit looked as though a bomb have been dropped on it.【解析】句意：房子里面乱七八糟，看上去好像落过一颗炸弹。当as though后面的从句表示与过去事实相反的假设时，从句谓语动词用had done。【答案】14.havehad15.Can I pay t

57、he bill by check?Sorry, sir. But in our hotel payment will be made in cash.【解析】句意：我可以用支票付账吗?对不起,先生。在我们酒店应当采用现金付款。shall用于第一，三人称的肯定句中，有“规定，命令”等意思，will没有这一用法。【答案】15.willshall16.They are brothers, but they do not always agree with each other as they can. Quarrels break out now and then.【解析】句意：他们是兄弟，但是他们

58、却并不像本来应该的那样志同道合。争吵时常发生。should应当。【答案】16.canshould17.What does the notice on the wall say?No person must take books out of the reading room; otherwise he would be fined.【解析】句意：墙上的通知说什么了?任何人不得把书拿出阅览室;否则,他将被罚款。must表示“禁止”时，只可用于肯定句中；shall用在第二、三人称的肯定句时，可表“规定，警告，威胁”等。【答案】17.mustshall18.What do you think of

59、your winning the game?On the one hand, I am proud of it; but on the other hand, I feel I must have done it better.【解析】句意：赢得这场比赛你感觉怎么样?一方面,我感到骄傲,但另一方面,我觉得我本能做得更好。could have done意为“本能够做(但没有)”。【答案】18.mustcould19.There is plenty of time for you to think about it carefully, so you mustnt rush now. Should you change your mind, please keep me informed.【解析】句意