【#文档大全网# 导语】以下是®文档大全网的小编为您整理的《情态动词课件》,欢迎阅读!
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情态动词
情态动词表示说话人对某一动作或状态认为可能、应当、必要等。情态动词有一定的词义,但不全,不能单独作谓语,必须和不带to 的不定式连用(ought )除外。 一、must 的用法
1.表示责任、义务,意为“必须”。 e.g. You must tell your reason. 2.强调语气的肯定,意为“一定要”。 e.g. I must ask you your name. 3.表示推测,意为“想必”。
e.g. Your brother must be in the library. I saw him just now. 4.作“偏偏”解时。
e.g. Just when we were about to go for an outing, our baby must catch a bad cold. must的否定式及其答语
1.当must意为“必须”时,否定式为needn’t, 其否定形式也可用don’t have to e.g. ---- Must I finish my homework now?
---- Yes, you must.& No, you needn’t/ don’t have to. 2. 当要表达“绝对不可,不许”时,其否定式为must not e.g. You mustn’t smoke , must you? 3.表示“推测”时,其否定式为can’t
e.g. He must be telling lies.→ He can’t be telling lies. 4.may作“允许”解时,可作它的否定答语 e.g. ---- May I come in? ---- No, you mustn’t. 二、can/ could 的用法 1.表示能力或客观可能性
e.g. A bird can fly. Anyone can make mistakes. 2.表示允许或许可,可代替may e.g. You can go home now.
Can I borrow two books at a time?
3.在否定句、疑问句中表示怀疑或推测 can/ could与be able to 用法的区别
1.在表示“能够”(本身能力或客观的因素)这个意思时,可以通用。 e.g. I am able to/ can swim well.
但be able to 还有将来时,完成时。
e.g. I have not been able to go to work for three days. 2.be able to 尤指在困难的情况下所具有的能力。 e.g. He was able to jump into the sea before the boat sank.
三、may/ might 的用法 1.may/ might 的意义
1)表示可能,意为“或许”,“也许” e.g. He may come or may not. 2) 表示许可,意为“可以”。
e.g. May I smoke here? Yes, you may. No, you mustn’t (can’t). 3)表示有理由这么说,意为“可以,不妨” e.g. You may criticize, but you cannot scold him.
4)表示祝愿,只用于肯定句。 e.g. May you succeed.(不用might) 5)用于从句,表示让步,意为“不管,无论”
e.g. Whoever may say so, you need not believe him. 2.may 和might
1)征求对方意见时,如主语是第一人称,既可用may 也可用might e.g.---- May( Might)I borrow you pen? ---- Yes, you may.
如果主语是第二、三人称时,不能用may 或might, 而要用can. e.g. Can you give a room for the night? (有过夜的房间吗?) 2)回答表示给予的问话时,不用might 而用may或can e.g. Might I give it to him? Yes, you may (can) 3.may和can
1) 二者都可表示“许可”
e.g. May( Can) I have a word with you?
2) 在“If I may say”和“If I may ask”等习惯用法里,仍用may 不用can e.g. How much time did it take, if I may ask? 四、ought to 和 should的用法
1.ought to 和should用来表示义务或责任 e.g. You oughtn’t to / shouldn’t drink and drive. 2.用来表示劝告或推荐(ought to和should) e.g. You should /ought to stop smoking
3.ought to和should 用来表示试探性的推断 e.g. We ought to / should arrive before dark.
注:ought to 语气比should 强。Ought to 中的to 不可省略。但在回答时,可省。e.g. Ought he to go? Yes, I think he ought (to). 五、will (would) 的用法 1.will的意义
1)表示一种有意识的行动,意为“愿,想,要”。 e.g. I will tell you an interesting story.
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2)will与第二、三人称连用,可表示一种必然性。 e.g. If he says he’ll come, he will.
You will be glad to see her. 见到她你会高兴的 2. Would的意义
1)表示强烈愿望、意愿,可用于一般现在时。
e.g. “I would do anything for our soldiers.” said the boy. 2)表示过去的习惯性
e.g. On Sundays he would come and work with us on those days. 3)表示请求,语气比will委婉。 e.g. Would you take a seat? 4)wouldn’t 表示请求,用于邀请,而不是否定意思。 e.g. Wouldn’t you like some coffee?
You’d like some tea, wouldn’t you?
但would you not…?的意思是否定的,相当于一个否定的祈使句。 e.g. Would you please not smoke? Would you please not be late? 六、used to 和would 1)would 主要表示与过去另一段时间相比,常与表示过去的时间状语连用,意为“总要,总是”
Used to 主要表示与现在的时间相比,意为“过去经常” e.g. The door wouldn’t open. 这门老是打不开。
I used to get up early. (言外之意,现在不早起)
2)used to 还可与状态动词连用,表示过去的状态,而would不可。 e.g. He used to be a quiet boy. (√) He would be a quiet boy. (×) 七、must 和have to
1)must 表示个人意志或主观上的必要性 Have to 表示客观需要。译为“不得不” e.g. We must study hard.
I have no bike. I have to go to the office on foot.
2) have to 的否定式和疑问式都借助于do,且have to时态较多,有将来时,完成时等。 八、need 和dare 的用法
1.need 和dare在否定句,疑问句,条件句中常用作情态动词,在肯定句中常用作实义动词。但I dare say 特殊。
2.need作为情态动词,没有时态变化。 dare作为情态动词,过去时为dared
3.need 和dare的做题思路是:从备选答案入手,是情态动词就应符合情态动词用法,后接动词原形,否定式在need, dare后直接加not,疑问句将need ,dare置于主语前,是实义动词应符合实义动词用法,后接带to的不定式。否定句,疑问句都应借助于do 或do 的变形。
e.g.1)You_____ to the meeting this afternoon if you have something more important to do.
A. needn’t to come B. don’t need come
C. needn’t come D. don’t need to be coming 2)The little girl______ the street by herself. A. dared not to cross B. dared not cross
C. don’t dare cross D. didn’t dare crossing 九、情态动词的其它用法 1. 可表推测的情态动词
can, could, may, might, must, should 都可用来表示推测 情态动词+原形动词表示对现在情况的推测。情态动词+have done表示对过去情况的推测
1) can常用于否定句或疑问句,用于肯定句时,表一时的可能性 e.g. The temperatures can fall to -60℃ in winter in Canada 2)could常用于肯定句,否定句
3)may, might常用于肯定句,否定句 4)must只用于肯定句。否定句用can’t 5)should表示试探性的推测
e.g. They should have arrived in Beijing by this time 2.可表“原本…而未…”的情态动词
should (could, might, ought to)+have done 可表示“原本…而未…” 另外:needn’t have done 表示“本不必” e.g. We needn’t have waited for him.
再有:was(were) going to + 不定式也可表示过去本该而未实现的事 e.g. He was going to have a talk with me yesterday afternoon.
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