情态动词及虚拟语气讲解

精品文档 1欢迎下载 情态动词情态动词 结构图结构图 概述概述 can 和 could 的用法 may 和 might 的用法 must 的用法 need 和 dare 的用法 情态动词情态动词 基本用法基本用法 shall 和 should 的用法 will 和 would 的用法 ought to 的用法 used to 的用法 had better 与 would rather 的用法 情态动词情态动词情态动词 must must must can can can could could could may may may mightmightmight 其它用法其它用法其它用法其它用法 表推测的用法表推测的用法表推测的用法 情态动词 have done 结构的含义及用法 一 概述一 概述 情态动词有 can could may might must must have to shall should will would need need dare dared ought to 情态动词无人 称和数的变化 不能独立使用 它与其后边的动词原形一起构成谓语 情态动词的具体用 法如下 二 情态动词的用法二 情态动词的用法 一一 cancan 和和 couldcould 的用法的用法 l 注意 can 和 could 的一般疑问句的回答 could 用在疑问句中比 can 语气更委婉 如 Can you finish this work tonight Yes I can No I can t Could you help me Sure Certainly OK Of course 或 Yes I can No 或 Sorry I m afraid not 2 can 和 could 表示推测 见后面 3 can 与 be able to 的区别 精品文档 2欢迎下载 can 常常指某人具备某种知识或技能 而 be able to 则指具体做某件事的能力 如 I can read but I am not able to read this passage can 常常只有现在或过去两种形式 而 be able to 可以有多种形式 可以用于多 种时态 如 Jim can read and write now but he couldn t do it when he was four years old At that time he was able to answer the question now he is able to answer the question too Of course he will be able to answer such question easily in the future 二二 maymay 和和 mightmight 的用法的用法 1 注意 may 与 might 的一般疑问句的回答 might 用在疑问句中比 may 语气更委婉 用 May I 征询对方许可在文体上比较正式 在口气上比较客气 在日常口语中 用 Can I 征询对方意见在现代口语中更为常见 如 May Might I ask you some questions Yes you may Yes you can Yes you must Yes please No you may not 一般不常用 No you can t No you mustn t No you d better not 2 may 和 might 表示推测 见后面 3 用于祈使句中表示祝愿 例如 May you succeed 三三 mustmust 的用法的用法 1 注意 must 的一般疑问句的回答 Must I go there at once Yes you must No you needn t No you don t have to 2 must 表示推测 见后面 3 must 与 have to 的区别 must 只有一种形式 而 have to 有各种形式和时态 随 have 的变化而定 must 表示的是说话人的主观看法 而 have to 则往往强调客观需要 例如 The play is not interesting I really must go now I have missed the bus so I have to walk home I had to work when I was your age 精品文档 3欢迎下载 四四 needneed 和和 daredare 的用法的用法 1 作情态动词 need 表示 需要 或 必须 仅用于否定句或疑问句中 在肯定句中一般用 must have to ought to 或 should 代替 注意其一般疑问句的回答方式与 must 完全 一样 dare 主要用于疑问句 否定句和条件状语从句中 一般不用于肯定句 例如 You needn t come so early Need I finish her work today Yes you must No you needn t No you don t have to Dare he do it No he daren t How dare you say I m unfair If you dare come here I will come to meet you He daren t speak English before such a crowd dare he Yes he dare No he daren t 注意 needn t have done 表示本来不必做某事而实际上却做了某事 例如 You needn t have waited for me 2 作实义动词 dare 和 need 后面接不定式 to do 有人称 数和时态的变化 变否定句和疑问句 时要借助于助动词 所不同的是 作实义动词时 在肯定句中 dare 后面通常接带 to 的 不定式 而在否定和疑问句中 dare 后面的不定式可以不带 to 例如 I dare to swim across this river He does not dare to answer Don t you dare to touch it I wondered he dare to say that Does he dare to go there Yes he does No he doesn t He needs to finish it this evening He doesn t need to finish it this evening Does he need to finish it this evening Yes he does No he doesn t 五五 shallshall 和和 shouldshould 的用法的用法 1 Shall 的用法 shall 用于第一人称的肯定句表示将来 用于第一人称的特殊疑问句表示征求对方 的意愿 例如 I shall go to Beijing tomorrow What shall we do this evening shall 用于第一 第三人称疑问句中 表示说话人征求对方的意见或向对方提出 请示 例如 Shall we begin our lesson When shall he be able to leave the hospital 精品文档 4欢迎下载 shall 用于第二 三人称的肯定句中 表示说话人给对方的命令 警告 允诺或 威肋 例如 You shall fail if you don t work harder 警告 He shall have the book when I finish reading 允诺 He shall be punished 威胁 2 should 的用法 should 的用法 a should 表示劝告 建议 命令 其同义词是 ought to 如 You should go to class right away Should I open the window b should 可以用在 if 引导的条件从句中 表示一件事听起来可能性很小 但也不是 完全没有可能 相当于 万一 的意思 从句谓语由 should 加动词原形构成 主句谓语却不 一定用虚拟语气 例如 Ask her to ring me up if you should see her 你万一见到她 请让她绘我打个 电话 If you should change your mind please let us know 万一你改变主意 请通 知我们 Should I if I should be free tomorrow I will come 万一我明天有时间 我 就来 c Why How should 结构表示说话人对某事不能理解 感到意外 惊异等意思 意为 竟会 例如 Why should you be so late today 你今天怎么来得这么晚 Where is Betty living 一 How I should know 贝蒂住在哪里 我怎么会知 道呢 I don t know why you should think that I did it 我真不知道你凭什么认为这件事是 我干的 d should have done 表示本应该做到而实际上没有做到 You should have started earlier ought to 的用法 a ought to 也表示 应该 注意其肯定句 否定句 一般疑问句及回答 You ought to obey the law You oughtn t to obey the law Ought you to obey the law Yes I ought to No I oughtn t to 精品文档 5欢迎下载 b ought to have done 表示 按规则 过去应做某事而实际未做 例如 You ought to have helped him but you didn t 这时 ought to 与 should 可以互相换用 注意 在美国英语中 ought to 用于否定和疑问句时 to 可以省略 例如 Ought you smoke so much You oughtn t smoke so much should 与 ought to 的区别 should 侧重表示道德上理应如此 而 ought to 侧重表示在规则 条例或法律上应该 如此 如 You should go to class right away According to the law you ought to obey the rules 六六 willwill 和和 wouldwould 的用法的用法 1 will 的用法 will 表示请求 建议等 例如 Will Would you pass me the book 表示意志 愿望和决心 例如 I will never do that again They asked as if we would do that again 2 would 的用法 would 是 will 的过去式 注意其两种固定问句的回答方式 Would you like Yes please No thanks Would you like to do Yes I d love to I d love to but I m sorry I can t would 与 used to 的区别 would 表示过去反复发生的动作 没有 现已无此习惯 的含义 而 used to 表示过去 反复发生的动作或某种倾向 有 现已无此习惯 的含义 例如 He used to come here early but now he doesn t do it He said he would write many novels when he was young He used to be a teacher but now he isn t 3 will 与 would 的区别 would 比 will 委婉客气 用 will be 和 will have done 结构表示推测 主要用 于第二 三人称 前者表示对目前情况的推测 后者表示对已经完成的动作或事态的推测 精品文档 6欢迎下载 而 would be 和 would have done 表示料想或猜想 例如 This will be the book you want He will have arrived by now It would be about ten when he left home What would she be doing there I thought he would have told you all about it 七七 oughtought toto 的用法的用法 1 ought to 也表示 应该 注意其肯定句 否定句 一般疑问句及回答 You ought to obey the law You oughtn t to obey the law Ought you to obey the law Yes I ought to No I oughtn t to 2 ought to have done 表示 按规则 过去应做某事而实际未做 例如 You ought to have helped him but you didn t 这时 ought to 与 should 可以互相换用 注意 在美国英语中 ought to 用于否定和疑问句时 to 可以省略 例如 Ought you smoke so much You oughtn t smoke so much 八八 usedused toto 的用法的用法 used to 表示过去的习惯动作或状态 现在已不存在 would do 只能表示过去习惯 性的动作而不能表示过去的状态 并且这种动作现在也可能存在 在间接引语中 其形式 可不变 注意在疑问句 否定句 否定疑问句或强调句中 可有两种式 例如 He told us he used to play football when he was young 疑问句 Did you use to go to the same school as your brother Used you to go to the same school as your brother 否定句 I usedn t to go there I didn t use to go there usedn t 亦可拼作 usen t 但发音皆为 ju znt 否定疑问句 Usen t you to be interested in the theatre Didn t you use to be interested in the theatre 精品文档 7欢迎下载 强调句 I certainly used to smoke but it was a long time ago I certainly did use to smoke but it was a long time ago 其反意疑问句或简略回答中 也有两种形式 She used to be very fat didn t she use d n t she Did you use to play chess Yes I did Used you to get up early in the morning Yes I did Yes I used to 九 九 hadhad betterbetter 与与 wouldwould ratherrather 的用法 的用法 1 had better 意为 最好 后接不带 to 的不定式 例如 We had better go now Yes we had we d better we better had Hadn t we better stop now Had we better not stop now I think I d better be going 用于进行时态 表 最好立即 You had better have done that 用于完成时态 表未完成动作 注 had best 与 had better 同意 但较少用 You had better 用于同辈或小辈 对长辈不可用 2 would rather 意为 宁愿 表选择 后接不带 to 的不定式 例如 I d rather not say anything Would you rather work on a farm Wouldn t you rather stay here No I would not I d rather go there 由于 would rather 表选择 因而后面可接 than 例如 I would rather work on a farm than in a factory I would rather watch TV than go to see the film I would rather lose a dozen cherry trees than that you should tell me one lie I d rather you didn t talk about this to anyone 句中的 d rather 不是情态动词 would 在此是表愿望的实义动词 附 情态动词表示推测及附 情态动词表示推测及附 情态动词表示推测及附 情态动词表示推测及 情态动词情态动词 have done have done 结构结构 分析分析 一 情态动词一 情态动词一 情态动词一 情态动词 must must must must can can can can could could could could may may may may mightmightmightmight 表推测表推测表推测表推测 精品文档 8欢迎下载 的用法 的用法 的用法 的用法 情态动词中的 must can could may might 都表推测 其中 must 的可能性最大 can could 次之 may might 最小 具体用法如下 1 1 它们出现的句型不同 它们出现的句型不同 must 常用于肯定句中表推测 can 常用于否定句和疑问句中表推测 也可以用于肯定 句中 但不常见 could 常用于肯定句 否定句和疑问句中表示推测 may might 常用于 肯定句和否定句中表推测 might 表推测时比 may 的可能性更小 如 He must be a teacher He can t be a teacher Can he be a teacher The weather can be quite warm in winter The plane could be delayed by fog It couldn t possibly be poison He may might be a teacher He may might not be a teacher Can he be a teacher You must have been to Shanghai If you come here earlier yesterday you could have met him He can t couldn t have been to the town Can he have been to the town Where can could they have gone He may might have finished the work He may might not have finished the work 2 2 有两种不同的推测形式 有两种不同的推测形式 can could may might must be 表示对现在情况的推测 而 can could may might must have done 则表示对过去的推测 must be 为 肯定是 一定是 can t couldn t be 为 不可能是 may might be 为 可能是 may might not be 为 可能不是 must have done 肯定是做过 can could not have done 不可能 已经做过 may might have done 可能已经做过 may might not have done 可能没有做过 例子见上面 3 3 注意变反义疑问句 注意变反义疑问句 如果它们后面接 be 表示对现在的推测 变反义疑问句时 应将其当成 be 动词一般 现在时态看待 如 He must be a teacher isn t he He can t be a teacher is he He may be a teacher isn t he He may not be a teacher is he 如果它们后面接 have done 表示对过去的推测 变反义疑问句时 如果句中有了表 示过去的具体的时间状语 应将句子当作实义动词的一般过去时态看待 如果句中没有具 体的时间状语 应将句子当作现在完成时态看待 如 Lucy must have gone there 精品文档 9欢迎下载 yesterday didn t she He must have finished his homework hasn t he 下面这些短语不具有推测含义 could have done 本来能够做 而没有做 ought to have done 本来应该做 而没有做 表示从客观法律 义务或规则上看应该做 而没能做到 should have done 本来应该做 而没有做 表示从主观上看应该做 而没能做到 needn t have done 本来不需要做 而已经做了 如 We could have come here an hour earlier You ought to have finished your homework You needn t have come here early 4 4 注意 注意 must 表示推测时很少用于将来的情况 一般不用 He must come tomorrow 可用 It s certain I m sure that he will come tomorrow may might 可以推测将来的情况 如 I think we should take raincoat with us it may rain 我想我们应该带上雨衣 可能要下雨了 She might not come this afternoon 她今天下午可能不来了 二 二 情态动词情态动词 have done have done 结构的含义及用法结构的含义及用法 1 1 shouldshould havehave done done shouldshould notnot havehave donedone 它们分别表示 过去本来应该 已经 而实际上并没有 过去本不应该 已经 而实际上却已经 如 We should have studied last night but we went to the concert instead 我 们昨晚本应学习的 但我们却去看音乐会了 实际上没有学习 If he had joined us we should have had a more enjoyable time 如果他加入 我们的活动 我们就可以玩得更开心了 实际上没那么开心 由于他没加入我们的活动 I should have thought of that 这一点我应该想到的 但实际上没想到 They shouldn t have left so soon 他们不应当走得那么早 但实际上还是走了 He shouldn t have said such a thing 他当时不应该说那种话 但已经说了 在表示推测时 它表示的是 大概已经 或许已经 的意思 如 The train should have already left 火车大概已经开走了 Time is up you should have finished your exercises 时间已到 你们可能已 精品文档 10欢迎下载 经做完作业了 2 2 wouldwould havehave donedone 它表示的是与过去事实相反之假设的结果 意思是 当时就会 了 而实际上没 有 如 I would have helped you if I had known of your difficulties 要是我当时知 道你们的窘境 我就会帮助你了 而实际上没有帮助你 If it hadn t rained yesterday we would have gone on excursion 假如昨天没 下雨 我们就去远足了 实际上没有去 在表示推测时 它表示 过去大概是 似乎 可能 如 I suppose the writer would have been about thirty when he published his first work 我想这位作家出版第一部作品时 大概是 30 岁左右 3 must3 must havehave donedone 它表示 过去一定 了 且结果延续到现在 用于对过去发生的事进行推测 如 No one answers the phone call they must have already gene out 没人接电话 他们一定已经出去了 They must have arrived by now 现在他们想必已经到达 You must have known what he wanted 你当时一定知道他要什么 Where is my pen I must have lost it 我的钢笔在哪 我肯定把它弄去了 4 cannot4 cannot havehave done couldn tdone couldn t havehave donedone 这两个形式表示 过去应该不可能做 如 He can not have promised it 他应该不会答应那种事 John is very clever He cannot have told his son to do that 约翰是很聪明 的 他应该不会叫他儿子那样做 He couldn t have said such a thing 他应该不会说出这样的事 5 can t5 can t havehave donedone 它表示 过去不可能做 如 She can t have gone to school we have no school today 她不可能到学校去 今天我们学校放假 He can t have finished the work so soon 这项工作他不可能完成得这样快 Jack doesn t work hard at all He can t have passed this English 精品文档 11欢迎下载 examination 杰克学习根本不用功 他不可能通过这次英语考试 6 can6 can could could havehave donedone 这种形式只用于疑问句 表示 含疑问语气的推测 如 Where can could they have gone 他们能到哪里去了呢 How could he have forgotten such an important thing 这么重要的事他怎么能忘 了呢 He told me he had a meeting to attend in Beijing Can he have gone to Beijing to attend the meeting 他告诉我说北京有个会议要参加 他会不会已位去了北 京呢 Can you have left the watch at home 你会不会把表丢在家里呢 7 could7 could havehave donedone 它表示 过去本来能够 实际上没能做 如 I could have run 100 meters in 12 seconds 我本来能用 12 秒钟完 1