高中英语必修三 Unit 5 The Value of Money 5.2 Discovering Useful Structures

1、Unit 5 The Value of MoneyDiscovering Useful Structures2Read and pay attention to the words in bold. Step 1. Lead in情态动词表示说话人对某一动作或状态的态度，本身不能单独作谓语，必须和不带to的不定式(即动词原形)连用。情态动词没有人称和数的变化。一、情态动词Step 2. Presentation1.can和could (could是can的过去式，语气更委婉)合作探究1能力许可可能可能性可能再也不为过can表示推测。can表推测时一般用于否定句和疑问句中(could一般无此限制

2、)。表示对过去发生的行为怀疑或不肯定时, 常用“can/could+have+过去分词”的否定或疑问形式。It cant/couldnt be true. 那不可能是真的。Can/Could he have heard the news? 他听说过这个消息了吗? can表示客观的、一时的情况, 意思是“有时候会”。The weather in Shanghai can/could be very cold in winter. 上海冬季可能很冷。表示惊异、怀疑, 不相信的态度(主要用在否定句、疑问句或感叹句中)。How can you be so careless! 你怎么那么粗心呀! 2.m

3、ay和might合作探究2May I play computer games after supper?Yes，you may./No，you mustnt.They may/might be having a meeting，but Im not sure.If you are interested，you may/might as well try.自主发现2(1)句中may表示_。否定回答时，用_。(2)句中may和might表示_，_可能性更小。(3)句中_，意为“不妨”。允许或征询对方许可mustnt可能性mightmay/might as well动词原形3.must与have t

4、o合作探究3I have to wait until the rain stops because I have no umbrella with me.我不得不在这儿等到雨停，因为我没带伞。(强调客观需要)I must recite the text this morning.今天早上我必须背会这篇课文。(强调主观意志)Must we hand in our homework today?Yes，you must./No，you dont have to/you neednt.You mustnt smoke here.Your mother must be waiting for you

5、now.你的母亲现在一定在等着你。Why must you always interrupt me？你为什么非要一直打断我呢？自主发现3(1)句中have to和句中must均表示“_”，但_是指说话人的主观看法，而_则强调客观需要。(2)句中must 所构成的疑问句，回答的否定形式通常为_或_，意为“不必要”，而一般不说_ (句中mustnt表示“禁止”)。(3)_句中must 常表示有根据的、比较确定的推测(只用于肯定的陈述句)，译为“一定，必定”。(4)句中must表示“_”。,必须musthave toneedntdont have tomustnt偏要，偏偏4.should和ough

6、t to合作探究4All visitors should/ought to take the tickets and masks.I find it astonishing that he should be so rude to you.他竟然对你这样无礼，真让我吃惊。Mr Lee asked if he should get his visa on time.李先生问能否按时拿到签证。自主发现4(1)句中should表示“_”，其同义词是_；在疑问句中，通常用_代替ought to。(2)句中should 有时可用于某些从句中，表示说话人惊奇、失望等感情色彩，常译为“竟然，怎么会”。(3)

7、句中should作为shall的过去式，用于第一、三人称作主语的疑问句，且多用于间接引语中，以征求对方的意见。义务、责任、建议ought toshould5.will和would合作探究5Would you pass me the coffee，please？She said that she would try her best to help the patients.Each time his mothers birthday came，he would buy her a present.每次到他母亲生日的时候，他都要给她买一件礼物。(表示过去的习惯)We will do our be

8、st to help the homeless child. Oil will float on the water.油总是浮在水面上。自主发现5(1)句中would表示_，比will更委婉客气。(2)句中would和句中的will表示_。(3)句中would和句中的will表示习惯性动作或客观真理。would表示过去的习惯性动作时，暗示现在仍然如此；而used to表示过去常常做某事，强调现在不是这样了。My father used to go to the office by bike when he was young.我父亲年轻的时候总是骑自行车去上班。(现在不是这样了)请求、建议意志

9、、愿望和决心6.dare合作探究6If he dare go，Ill go with him.如果他敢去，我就跟去。Tom didnt dare to break the rules.自主发现6(1)dare作情态动词时，表示“敢，敢于”。常用于否定句和疑问句中，后接动词原形，否定形式为dare not。(2)dare常用作实义动词，有时态、人称和数的变化，后面可接带to的不定式。7.had better合作探究7You had better ask the teacher for help. You had better not talk with strangers.你最好不要和陌生人讲话

10、。自主发现7had better表示“_”，使用时常缩写为_，无人称和数的变化，其否定式一般把not放在had better之_。最好d better后二、过去将来时1. 过去将来时表示从过去某一时间来看将要发生的动作或存在的状态, 常用在宾语从句中。一般由“would/should +动词原形”构成。She hoped that they would meet again someday. 她希望将来有一天他们能再见面。I rang up to tell my father that I should leave for London. 我打电话告诉我父亲我要去伦敦。2. was/were

11、going to+动词原形: 表示过去将要发生或很有可能发生的动作, 常用于口语中, 表示预言、意图或者打算等。He was going to start work the following week. 他打算下星期开始工作。Alice, why didnt you come yesterday? 爱丽丝, 你昨天为什么没来呀? I was going to, but I had an unexpected visitor. 我打算去的, 但我家来了个不速之客。3. was/were about to do: 常用来表示即将发生的动作, “刚要/正要做”。注意该结构不与任何时间状语连用。I

12、felt that something terrible was about to happen. 我感到某种可怕的事情即将发生。We were about to go there when it began to rain. 我们刚打算去那儿, 这时天下起了雨。4. start, go, come, leave, see, meet等动词的过去进行时: 表示就过去某一时刻而言即将发生的动作。She was coming later. 她随后就来。I had just put on my overcoat and was leaving to visit a friend of mine. 我

13、刚穿上外套要去看我的一个朋友。5. was/were to do: 表示“曾计划做某事”, 如果表示“本来计划做某事, 动作没实现”, 则需用 “was/were to have done”。She said she was to have told me about the accident. 她说她本来想告诉我关于事故的事。He said he was to meet his friend at the station at 4 p. m. 他说他下午四点去车站接他的朋友。1(1)选词填空：can，could，couldnt，be able toSamuel，the tallest boy

14、 in our class，_ easily reach the books on the top shelf.It was really annoying; I _ get access to the data bank you had recommended.It was so noisy that we _ hear ourselves speak. _ I have a word with you? It wont take long.cancouldnt couldntCanStep 3. Practice(2)补全句子I _ for your kindness.我再怎么感谢你的好意

15、也不为过。Keep working on it! You _ for the exam.继续努力！准备考试再充分也不为过。cannot thank enoughcant prepare too much2(1)用适当的情态动词填空You _ feel all the training a waste of time，but Im a hundred percent sure later youll be grateful you did it.Life is unpredictable; even the poorest _ become the richest._ I smoke in th

16、is room?No，you _.(2)补全句子I neednt wait，I _ you now.我不必等了，不妨现在就告诉你。maymightMaymustntmay/might as well tellStep 3. Practice3选词填空：must，neednt，have to，mustntCant you stay a little longer?Its getting late.I really _ go now.My daughter is home alone.You _ be careful with the camera.It costs!_ I turn down t

17、he radio now?No，you _.My brother was ill，so I _ call a doctor in.mustmustMustneednthad toStep 3. Practice4补全句子It was sad to me that they，so poor themselves，_.他们这么穷竟然还带食物给我，这使我很难过。You _ the baby to the doctors.你应该把这婴儿带去看看医生。I asked the teacher if I _.我问老师我能否请一天假。should bring me foodshould takeshould

18、have one day offStep 3. Practice5选词填空：would，used toI still remember my happy childhood when my mother _ take me to Disneyland at weekends.Whenever I was in trouble，he _ help me.If I write a letter，_ you post it for me?I _ drink coffee，but now I drink green tea.wouldwouldwouldused toStep 3. Practice6

19、补全句子He _ say what he thought.他不敢说出他的想法。_ staying where she was?她还敢冒险呆在原来的地方吗？didnt dare (to)/dared notDare she risk7补全句子Its half past two.I think we _.现在两点半了。我想我们最好还是回家吧。You _ class any more.你最好不要再上课迟到了。had better go homehad better not be late for Step 3. Practice8补全句子I told him I _ at the station.我跟他说，我会到车站去给他送行。The sky went very dark and we thought it _ but it was a false alarm.天空变得黑沉沉的，我们以为要下雨了，不过只