1、Part Grammar情态动词()思维导图一、基本特征1.情态动词有一定的词义，不能单独作谓语，需和实义动词或系动词一起作谓语。She can speak English though she is six.尽管她才6岁但她会说英语。 2.情态动词一般无人称和数的变化，个别情态动词有现在时和过去时两种时态变化。They must be in the classroom.他们一定在教室里。3.构成否定句时，not放在其后面。The young man cant carry the big stone.这个年轻人搬不动那块大石头。4.情态动词后接动词原形。You should do as I t
2、old you.你得照我说的去做。He said I could use the computer.他说我可以用这台电脑。We should study hard for our motherland and ourselves.为了我们的祖国和我们自己，我们应该努力学习。二、基本用法1.can和could的用法(1)表示能力。She can ride a bike though she is only eight.尽管她才8岁但她会骑自行车。He could speak Japanese when he was young，but he has forgotten most of it no
3、w.他年轻时会说日语，不过现在已经忘得差不多了。(2)表示猜测，主要用于疑问句或否定句。(could比can可能性更小)Can he be in the reading room now?他可能在阅览室吗？No，he cant be in it.Because I saw him in the office just now.不，他不可能在(阅览室)。因为我刚刚在办公室看见他了。Where could/can he be now?他现在可能在哪儿？He could go to the cinema.他可能看电影去了。(3)表示许可或请求许可。(could比can语气更委婉)Can/Could
4、you tell me the way to the nearest bank?你能告诉我怎么去最近的银行吗？Could you do me a favour?请你帮我个忙好吗？Im sorry I couldnt go to your home to help you with your English today.对不起，今天我不能到你家去帮你学英语了。以上句子中的could不表示过去，could和can没有时间上的差别。名师点津can和be able to用法上的区别：(1)can只有现在式和过去式could，而be able to有更多的时态变化，可用于将来时、完成时和非谓语动词中。(
5、2)can一般指自身具有的能力，而be able to表示经过一段时间的努力后所具有的能力，相当于manage to do或succeed in doing。Without his hard work，he was not able to get good grades.如果没有他的努力，他是不能取得好成绩的。(经过努力)Babies can swim when they were born.婴儿们刚生下来时会游泳。(自身具有的能力)2.may和might的用法(1)表示许可或请求许可。(用might比用may更礼貌，语气更委婉)May I come in?我可以进来吗？肯定回答：Yes，yo
6、u may./Of course，you may.是的，请进。否定回答是No，you may not/you cant/you mustnt/you had better not.Might I ask you a question?我可以问你一个问题吗？He asked if he might borrow my pen.他问我是否可以借我的钢笔。(2)表示可能性。(might比may可能性更小)It may rain.Youd better take a raincoat with you.天可能会下雨，你最好带上雨衣。The news may be true.The news might
7、 be true.这消息也许是真的。He might not come today.今天他可能不来了。(might not较may not更不肯定)may用于祈使句，表祝愿，并且may通常放在句首。May you be happy！祝你快乐！May you succeed！祝你成功！May you have a good time on your trip!祝你旅途愉快！3.will和would的用法(1)表示意志、意愿。用于各种人称，will指现在，would指过去。I will never do that again.我再也不会做那件事了。(2)表示请求、建议。用于第二人称的疑问句，wou
8、ld表示更委婉的语气。常用句型：Would you please do.；Would you mind doing.；Would you like.Would you like a cup of coffee?你想来杯咖啡吗？(3)表示习惯性动作，意为“总是，习惯于”。will指现在，would指过去。On Sunday he would go to the park to play chess.以前每到星期天他总是到公园去下棋。易混辨析would，used towould表示过去习惯性的动作；现在可能如此，也有可能不再那样used to表示过去的动作或状态；现在不再做或不再有那种状态He w
9、ould go to the park as soon as he was free.过去，他一有空就去公园。(动作反复发生，现在还有可能再去)People used to believe that the earth was flat.过去，人们总以为地球是扁平的。(表示过去的动作，但现在已不再这样认为)4.shall和should的用法(1)shall的用法用于陈述句的第二、第三人称，表示允许、警告、命令、决心、威胁等；用于第一、第三人称的问句，表示征求对方意见。When shall he be able to leave the hospital?他什么时候能离开医院？You shall
10、 fail if you dont work hard.如果你不努力学习你会考试不及格。(2)should的用法表示劝告或建议，意为“应该”；表示可能性，这时should要比can，may更肯定；表示惊讶。Why should I be angry with you?我哪会生你的气呢？5. must的用法(1)表示必须。(must提出的问题，其否定回答用neednt，表示没有必要)All the students must obey the school rules.所有学生必须遵守校规。You must see that TV play；its wonderful.那个电视剧好极了，你不可不
11、看。Must I go now?我现在就得走吗？Yes，you must.是的，你现在就得走了。No，you neednt.不，你没有必要现在就走。(2)表示推测。(只能用在肯定句中，在否定句或疑问句中要用can或could)You must be tired after the long journey.长途旅行之后你一定累了。Betty must be in the next room.I can hear her talking there.贝蒂肯定在隔壁房间，我能听见她在那儿讲话。My watch doesnt work.There must be something wrong wi
12、th it.我的手表不走了，一定是出问题了。(3)must用于发生了某种与说话人的愿望相反、不受欢迎的事时，意思是“偏偏”、“偏要”、“非得”。Why must he go out in the bad weather?为什么他偏要在这种坏天气出门？Must you watch TV at midnight?你非得在半夜看电视吗？(4)must not表示禁止，意思是“不许”“不准”“不可以”等。You mustnt stop your car in the busy street.你不准把车停在繁忙的路上。Children mustnt speak to their parents in t
13、hat way.孩子们不准对他们的父母那样说话。用适当的情态动词填空1. George can not have gone to sleep，for the light was still on.2.It was really annoying；I could not get access to the data bank you had recommended.3.When you cross the street，you must be careful with the passing cars.4.It cant be his mother，for she has been ill at
14、 home for a long time.5.We enjoy good weather in January，but sometimes it can be terribly cold.6.I may/might come to the party with you，but I am not sure.7.When he was young，he would climb the small hill every morning.8.May I take this seat?Yes，you may/can.9.Tom comes from Australia，so he can speak English very well.10.If you can pass the driving test，you shall get a new car.