I.情态动词基本用法 情态 用 法 动词 能力（体力， can 智力，技能） 允许或许可 （口语中常 用） 可能性 （表猜 could 测， 用于否定 句或疑问句 中） （问句中 may 可以 表示请求） 可能，或许 （表推测） might 祝愿 （用于倒 装句中） 必须，应该 （表主观要 must 求） 肯定，想必 （肯定句中 表推测） 只好，
不得不 have （ 客 观 的 必 to 须， 有时态和 人称的变化） 应当 （表示义 ought 务责任， 口语 to 中 多 用 should） 用于一三人 称征求对方 意见 shall 用 于 二 三 人 称表示许诺、 命令、警告、 威胁等 应当，应该 （表义务责 should 任） 本该 （含有责 备意味） will 意愿，决心 请求，建议， 用在问句中 would would 比较委 婉 敢 （常用于否 dare 定 句 和 疑 问 句中） 需要,必须 need （ 常 用 于 否 定句和疑问 否定式 can not / cannot /can’t do Can…do…? couldn’t do May…do…? Might…do…? Yes,…can. No,…can’t. 疑问式 简答式
may not do might not do
Yes,…may. No,…mustn’t/can’t. Yes,…might No,…might not. Yes,…must. No,…needn’t/don’t have Yes,…do. No,…don’t. Yes,…ought. No,…oughtn’t.
must not/mustn’t do
don’t have to Do…have to do…? do ought not to/oughtn’t to Ought…to do…? do
shall not/shan’t do
should not/shouldn’t do
will not/won’t do Will/Would…do…? would not/wouldn’t do dare not/daren’t do need not/needn’t do Dare…do…? Need…do…?
Yes,…will. No,…won’t. Yes,…dare. No,…daren’t. Yes,…must. No,…needn’t.
句中） used to used 过去常常 （现 not/usedn’t/us Used…to do…? en’t to do 在已不再） didn’t use to Did…use to do…? do Yes,…used. No,…use(d)n’t. Yes,…did. No,…didn’t.
II.情态动词的重点知识 A computer _____ think for itself; it must be 表示能力的情态动词用 told what to do. can/could A. can’t B. mustn’t C. may not D. might not 表 示 许 可 时 用 ①—Could I call you by your first name? may/might ,can/could 都 可 —Yes, you______ 以，但在问句中用 could…? A. will B. could C. may D. might 或 might… ？ 以使口气委婉 ②Johnny, you _____ play with the knife, you 客气， 其回答一定要用 can 或 _____ hurt yourself. may ， 以 使 回 答 口 气 明 确 A. won’t/can’t B. mustn’t/may （ must 表 示 一 定 ， 必 须 ， C. shouldn’t/must D. can’t/shouldn’t mustn’t 表示禁止，不许可） 。 The fire spread through the hotel very quickly 在肯定句中 could 不可以用来 but 表示过去某一特定场合的能 Everyone _____ get out. 力，而要用 was/were able to。 A. had to B. would C. could D.was able to Peter ______ come with us tonight, but he 在肯定句中都可以用来表示 isn’t very sure yet. 可能。在含义上 must 语气最 A. must B. may C. can D. will 肯定,may 表示的是事实上的 而 can 表示的是逻辑上的可能性： 可能性。 Mary is in poor health. She can be ill at any times. 在 否 定 句 中 只 能 用 can 和 Michael ______ be a policeman, for he’s may。所以 can’t 时用以代替 much too short. mustn’t，语气比 may 更肯定。 A. needn’t B. can’t C. should D. may 中文可以翻译为不可能。 He may be very busy now. 在疑问句只能用 can，不能用 Can he be very busy now? may 和 must。 He must be very busy now. Can he be very busy now? need 作为情态动词只有一种 形式，只用于否定句和疑问 句。 If he dare come, I will kick him out. I don’t dare 作为情态动词用时有两 know whether he 种形式：dare 和 dared 两个词 dare say. 形， 除了可以用于否定句和疑 注意:He doesn’t dare(to)answer the question. 问句外， 还可以用于条件从句 （否定句） 或表示怀疑的句子中。 Does she dare(to)enter the dark room?（疑问 句）
表 示 “ 能 力、 许 可”的 can 和 may
表 示 “ 推 断、 判 断”的 can may, must
情 态 动 词 +have done 的 用 法
用于第一人称： 征求对方的意 What shall we do this evening? 见。 You shall fail if you don’t work harder. 警告 用于第二、三人称：警告、命 He shall have the book when I finish reading. 令、允诺、威胁等。 允诺 He shall be punished.威胁 You should(ought to) go to class right away. 劝告、建议、命令、应该做、 I should(ought to) help him because he is in 道义上的责任。 trouble. 请求、建议，would 比 will 委 Would you pass me the book? 婉客气。 I will never do that again. 表示意志、愿望和决心。 They asked us if we would do that again During the vacation he would visit me every would 可表示过去反复发生 week 的动作或某种倾向。 The wound would not heal. （伤口老是不能愈 合） It would be about ten when he left home. would 表示估计或猜想。 What would she be doing there? could+have done： 本可以做而 You could have done better, but you didn’t try 实际上未能做。 your best. cannot+ have done：表示对现 He cannot have been to that town. 在或过去行为的否定推测。 can+主语+ have done：表示 对过去行为的怀疑或不肯定 Can he have got the book? （用在疑问句中） 。 might(may)+ have done：对过 He may not have finished the work. 去发生的行为不太肯定的推 If we had taken the other road, we might have 测。 arrived earlier. must+ have done： 对过去发生 的行为肯定的推测。 You must have seen the film. 其 否 定 式 为 ： cannot have You cannot have seen the film. done。 You needn’t have watered the flowers, for it is going to rain. needn’t+ have done： 本来不必 注意：didn’t need to(have to)do： 要做的而实际上又做了。 没有必要做而实际上也没有做 I didn’t need to clean the windows. My sister did it 2 hours ago. You should have started earlier, but you didn’t. should(ought to)+ have done： She shouldn’t have taken away my measuring 本来应该做而实际上又没有 tape, 做。 其否定形式表示某中行为 for I worked to use it. 不该发生却发生了。 注意：He should have finished the work by now.（表推测）
类 别 与现在 事实相 反 与过去 事实相 反 用 法 例 句 从句动词：过去式（be 用 were） 主 句 动 词 ： should/would/could/might+do 从句动词：had+done 主 句 动 词 ： should/would/could/might+have+done 从句动词：过去式/should+动词原形 与将来 /were+to do 事实相 主 句 动 词 ： 反 should/would/could/might+动词原形 将虚拟条件从句中的 were， had, should 放到主 语之前，构成主谓倒装 If he were here, he would help us. If I had been free, I would have visited you. If it should rain tomorrow, we would not go camping. ①Should he come ,tell him to ring me up. ②Were I you, I would not do it. ③ Had I been free, I would have visited you. ①If he had listened to me, he would not be in trouble now. ②If he had told me yesterday, I should know what to do now. ③If I were you, I would have gone to her birthday party. ① He could have passed the exam, but he wasn’t careful enough. ② You should have come earlier. The bus left a moment ago. ---But for your timely warning, we ______ into great trouble. ---You know we’re friends. A. would get B. must have got C. would have got D. can’t have got Without the air to hold some of the sun's heat, the earth at night would be freezing cold. It would be only partly right to follow in this way. 如果用这种方式， 仅仅对了一 半。 Having known in time ,we might have prevented the accident.要是及时得知的话， 我们也许能阻止这场事故。
If 引 导的 条件 从句
省略 if 的 虚拟 条件 句
不同时间的虚拟：各遵守各的规则 混合 虚拟 条件 句 虚拟与陈述的混合：各遵守各的规则
but for+名词表示虚拟 条件
含蓄 虚拟 条件 句
without+名词表示虚 拟条件 动词不定式表示虚拟 条件
句子或主句中的谓语 动词的形式视具体情 况而定。这是考查考 生应变能力的最佳试 题。
副词 otherwise 表示虚 拟条件
连词 but 连接的句子表 示虚拟条件
Given more attention, the tree could have grown better. 如果多留心的话， 这树本来可 以长的更好。 I was too busy at that time. Otherwise, I would have called you.我当时太忙，否则我就给 你打电话了。 He _____fatter but he eats too little . A. would become B. would have become C. must become D. must have become ①与现在事实相反 He talks as if he knew where she was． ②与过去事实相反 He talks about Rome as if he had been there before. ③与将来事实相反 He opened his mouth as if he would say something. Turn on the light so that we can see it clearly. He suggested that we not change our mind. I wish I could be a pop singer. I wish I would have gone to Shanghai last month.
其它 状语 从句
as if/as though 引导的状语从句中动词用 did 或 had＋done 或 would／could／might＋do。 注意：as if/as though 引导的状语从句中也可 以用陈述语气： 当说话者认为所述的是真实的或极有可能发 生或存在的事实时： It sounds as if it is raining．听起来像是在下 雨。 He talks as if he is drunk．从他谈话的样子来 看他是醉了。 in order that/so that 引导的状语从句中动词用 can/could/may/ might/ would 等+do demand, suggest, order, insist 后接的从句中动 词为 should+do wish 后的从句中分别用过去式， 过去完成式和 should/would+do 表示与现在，过去和将来情 况相反
在 It is necessary / important / strange that… It is suggested / demanded/ ordered / requested It is strange that such a person that…等从句中， should be our friends. 谓语动词用 should+do It is time that… 句 型 中 动 词 用 过 去 式 或 should+do would rather 所接的从句中动词用过去式或者 过去完成式 If only 句型中动词常用过去式或者过去完成 式，表示强烈的愿望 It’s high time that we left/should leave. I would rather you stayed at home now. If only our dream had come true!
其它 句型 中
1. –Where are the children? The dinner ’s going to be completely ruined. --I wish they __________ always late. A. weren’t B. hadn’t been C. wouldn’t be D. wouldn’t have been 2. Maybe if I ______ science, and not literature then, I would be able to give you more help. A. studied B. would study C. had studied D. was studying 3. I _______ sooner but I didn’t know that they were waiting for me. A. had come B. was coming C. would come D. would have come 4. –Why didn’t you come to Simon’s party last night? --I wanted to, but my mom simply ________ not let me out so late at night. A. could B. might C. would D. should 5. –Shall I inform him of the change of the schedule right now? --I am afraid you ________, in case he comes late for the meeting. A. will B. must C. may D. can 6. –Pity you missed the lecture on nuclear pollution. --I _______ it, but I was busy preparing for a job interview. A. attended B. had attended C. would attend D. would have attended 7. –How is your new babysitter? --We ______ ask for a better one. All our kids love her so much. A. should B. might C. mustn’t D. couldn’t 8. The police still haven’t found the lost child, but they’re doing all they ______. A. can B. may C. must D. should 9. –No one _______ be compared with Yao Ming in playing basketball. --Oh, you are really his big fan. A. can B. need C. must D. might 10. It _______ be the postman at the door. It’s only six o’clock. A. mustn’t B. can’t C. won’t D. needn’t 11. –I left my handbag on the train, but luckily someone gave it to a railway official. --How unbelievable to get it back! I mean, someone ______ it. A. will have stolen B. might have stolen C. should have stolen D. must have stolen 12. I _______ through that bitter period without your generous help. A. couldn’t have gone B. didn’t go C. wouldn’t go D. hadn’t gone 13. –Will you read me a story, Mummy? --You _______ have one if you go to bed as soon as possible. A. might B. must C. could D. shall 14. If you ______ go, at least wait until the storm is over. A. can B. may C. must D. will 15. I _____ worry about my weekend—I always have my plans ready before it comes. A. can’t B. mustn’t C. daren’t D. needn’t