1、第四学时Grammar情态动词(二)1.ought to 的用法(1)表示应该，多指客观上有责任有义务干某事。语气比should 强烈。其否定形式为 ought not to(oughtnt to)动词原形。You ought to give your seat to the old lady.你应该给老太太让座。We oughtnt to be careless with our homework.我们不应马马虎虎地做作业。ought to，must和 have to 的区别：must 强调主观看法，have to 强调客观需要，ought to 表示义务和责任。You must finis
2、h your homework before 5 oclock.你必须在 5 点前完成作业。Youll have to be there before 5 oclock.5点前你得到那里。Such things ought not to be allowed to happen again.这样的事情不允许再发生。(2)表示对现在或将来某种可能性的推测，这种推测是有根据的，可信度较高。Mary ought to be here soon.She took the early bus.玛丽应该很快就到这了，她坐的是早班车。must与 ought to表示推测时的区别：Tony must be h
3、ome now.托尼现在一定在家。(语气肯定)Tony ought to be home now.托尼现在应该在家了。(语气不十分肯定)They must have won the game.他们一定赢了比赛。(猜测，语气肯定)They ought to win easily.他们应该很容易能取胜。(推测，语气不太肯定)(3)“ought tohave 过去分词”表示过去应该做某事而实际未做。可以和 should互换。You ought to have taken care of him.你本来应该去照顾他的(但你没有)。2“情态动词 have done ”，表示猜测和估计。(1)must h
4、ave done用于对过去肯定的猜测。You look tired.You must have stayed up late last night.你看起来很累，昨晚你肯定熬夜了。She ran to the hospital in a hurry.Something terrible must have happened.她急匆匆地赶往医院，肯定发生了糟糕的事。(2)may/might have done也是对过去的猜测，语气没有 must强烈。Tom may have gone shopping with his neighbor.But I am not sure about it.汤姆
5、可能和他的邻居买东西去了，但我不太确定。(3)can/couldhave done 表示过去本来能够做某事但实际未做，也可表示过去有可能做过某事。can t/couldn t have done 表示过去不可能做过某事，即对过去的否定推测。Kelvin has gone to Beijing，so you couldn t have seen him yesterday.凯文去了北京，所以你昨天不可能看到他。Someone must have broken into our bedroom.Who could have done it?我们的卧室肯定有人闯入过，谁会这么做呢？My Englis
6、h exam sucks.I could have been more careful.我的英语考试考砸了，我本可以更仔细一些的。3.“情态动词 have done ”（形式表示虚拟语气）(1)should/ought to have done 表示过去本该做某事而没有做。The roses are dead.I should have given them more water.玫瑰花死了，我本应该给它们多浇水的。Think about the time you have wasted.You ought to have studied harder，but it was too late.
7、想想你浪费的时间，你应该更努力学习的，但现在太晚了。(2)shouldn t/oughtn t to have done表示过去不该做某事却做了。Your mother is very sad.You shouldn t have said those words to her.你妈妈很伤心，你不该对她说那样的话。(3)neednt have done 表示本不必要做的事情却做了。Your home is not far away from school，so you needn t have left in such a hurry.你家离学校不远，你不必这么急匆匆地离开。(4)would
8、rather have done表示过去本想做某事却未能做。I would rather have come to your party,but I was busy preparing my speech.我本想去参加你的晚会，但我在忙于准备我的演讲稿。4.“should 动词原形”表示：(1)应该You should finish it today.你应该今天完成任务。(2)惊讶，奇怪，居然It s strange that he should be so upset.他居然这么难过，真是奇怪。典例剖析1.（2012浙江卷）Had they known what was coming ne
9、xt,they _ second thoughts.A.may have B.could haveC.must have had D.might have had解析：虚拟语气中的情态动词。本句是一个倒装句，可还原为：if they had known what was coming next,they might have had second thought。根据had known提示，可知是与过去事实相反，因此虚拟语气主句中应该用would/might+have done，由此可见答案D符合语境。答案：D2Jack described his father，who_ a brave bo
10、y many years ago，as a strongwilled manA.would be B.would have beenC.must be D.must have been解析：考查情态动词推测用法。句意为“杰克把他的父亲描述为一个意志坚强的人，他的父亲多年前肯定很勇敢”。用must have been表示对过去事情的肯定推测。答案：D3Sorry,Professor Smith.I didnt finish the assignment yesterday.Oh,you _have done it as yesterday was the deadline.A.must B.mu
11、stntC.should D.shouldnt解析：考查情态动词的用法：情态动词 have done。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一、单项选择1._I return the dictionary within three days?No,you_.You_keep it for five days.A.May;neednt;willB.Can;mustnt;wouldC.Must;dont have to;canD.Shall;cant;should答案：C2.Sir,you_be sitting in this waiti
12、ng room.It is for women and children only.A.oughtnt to B.cantC.wontD.neednt3.She is already two hours late.What_to her?A.can have happenedB.must have happenedC.should have happenedD.must happenAA4.Mary_the job he offered to her,but she didnt.A.cant take B.ought to have takenC.should take D.must have
13、 taken5.He sat at the desk,_ a novel.A.readB.to readC.readingD.readsBC二、用合适的情态动词填空1What sort of house do you want to have?Something big?Well,it_ be bigthats not important.2Do you know where David is?I couldn t find him anywhere.Well.He _have gone farhis coats still here.1neednt 2.cant3Whats the name
14、?Khulaifi._ I spell that for you?4When crossing the street,you_ be too careful.5Shall we go out tonight?I _stay home.I have work to do.3.Shall 4cant5.would rather三、完成下列句子1.I prefer to walk_（也不愿）a bus.2.Tom used to _（靠谋生）delivering milk.3You _(不应该抽烟)so much.4You _(本应该汇报)this to the manager immediatel
15、y you found out he was stealing.5My dictionary_(不可能拿错)by mistake,for it was marked with my name.1rather than take 2earn his living by 3oughtnt to smoke4should have reported5couldnt have been taken四、语法填空Miss Jenkins was born in 1._rich family.She liked all the foods which were rich 2._fat and sugar.S
16、o she got fatter and fatter.Her workmates often laughed at her for it and said she 3._to lose weight.She was angry with them and 4._ get on well with them.Her weight brought her some trouble.No young man liked a fat girl 5._her and now she was more than thirty，but she 6._to live alone.She went to se
17、e the doctors.7._gave her a list of healthy diets and advised her to do more exercises and of course it was difficult for her 8._(do)so.For example，she went to a restaurant one day 9._ bought a nice cake.The waiter asked her how many pieces she wanted him to cut it into.She thought for a while and said she was losing her weight,so the cake 10._be cut only into two,not into six.1a2.in3.ought4.couldnt5.like6.had7.They8.to do9.and10.should
