1、情態動詞專題講義英文中的情態動詞主要有： can , could ; may , might ; must ; ought ; need ;dare , dared, 另外， shall , will , should , would 在一定的場合也 可用作情態動 詞。情態動詞表示說話人對某一動作或狀態的態度， 可以表示“可能”、 “可 以”、 “需要”、“必須”或“應當”等之意。情態動詞沒有人稱和數的變化。但不能單獨作謂語動詞用，必須和不帶 to 的不定式連用構成謂語動詞。只有情態動詞 ought要和帶 to 的動詞不定式連用，在句中作謂語用。將情態動詞置于主語之前即構成其疑問式，在情態動詞

2、之后加 not 既構成其否定式?，F將各情態動詞的基本用法分述如下：一、悄態動詞的本義用法1、can 和 could (could為 can 的過去式 ) 的基本用法(1) 表示能力：如： He can speak English better than you. 在疑問句和否定句中表示“懷疑”、“猜測”或“可能性”女口： Can this green bike be Liu Dong ，s?(3) 表示許可”時 can 可以和 may 換用：如： You can (may) go home now.(4) 如果要表示語氣婉轉，可用 could 代替 can, 這時 could 不再是 can

3、的過去 式。 (注意在回答中不可用 could) 。- Could I have the television on? Yes, you can. / No, you can ，(5) can 和 be able to兩者都可表示能力，兩者在意思上沒有什么區別。但是 can 只能有現在式 和 過去式，而 be able to 則有更多的形式，當表示成功地做了某事時，只能用 was/were able to, 如: He was able to swim across the river? （已經做過）He can swim across the river. （有這個能力，但還沒有實現）2、m

4、ay和might （might為may的過去式）的基本用法（ 1）表示允許或征詢對方許可，有 可以”之意，如: You may use mydictionary.在回答對方說“可以做某事”或“不可以做某事”時，一般多不用may或may not, 以避免語氣生硬或不容氣。而用比較婉轉的說法進行回答 .如 - May I use this dietionary? - Yes, please/ -Certainly.- I * m afraid not, because I am using now?但是表示“阻止”或“禁止”對方做某事時 , 要用 must not 代替 may notNo, yo

5、u mustn t ? It s too如: May I have a look at your new computer?- May we swim in this lake? dangerous ?注意：在請求對方許可時，如果 Might I？就比用May I？語氣更婉轉2）may 用于祈使句中表祝愿，如 :May you succeed!3、 must 的基本用法(1) must 表示“必須”、“應該”之意，其否定式 must not, 縮寫形式為 mustnt, 表示不準”、 不許可”或 禁止”之意，如： We must study hard and make progress eve

6、ry day.(2) 對以 must 提出的疑問句，如作否定回答時，要用 neednt 或用 don， t (doesn ，t) have to(不必)來回答，而不用 mustnt, 因為 mustnt 表示的是 禁 止”或“不許可”之意如：- Must we finish the work tomorrow?- No, you neednt (dont have to), but you must finish it in three days.(3) 表示“偏要，非得”一個?？贾馀冢?Why must you always interrupt me?你為什么非得老是打擾我 ？Must

7、you make so much noise? 你就 7IF ?得弄這么大聲嗎？4、Should 的基本用法(1) Should 和 ought to 后都接動原，指“應該”，表命令，勸告或建議等 . 但 ought to 強調道義、法律所規定的職責；而 should 一般是表示說話者的一種 主觀 看法。如： We ought to respect our teachers and parents.我們應該尊敬老師 和父母親。You ought not to be so careless in your work. 你不應該在工作上如此 粗心大意。(2) 表示說話人的感惜。如驚奇、憤怒、失望等

8、，“竟然”。如 You can t imagine that a well-behaved gentleman should be so rude to alady.- When can I come for the photos ? I need them tomorrow afternoon.- They be ready by 12 ： 00 ? （ ）A. can B. should C ? might D ? need5、Shall 的基本用法（1） . shall 用于笫一、三人稱疑問句中，表示說話人征求對方的意見和向 對方請示。Shall we begin our class?（

9、征求意見） When shall Mike be able to leavehospital? （請示）（2） . shall 用于第二、三人稱陳述句中，表示說話人給對方的命令，警 告，允諾，決心或威脅。You shall go with me.（命令） You shall have the book when I finish it.（諾）He shall be punished.（威脅）（3）. 用于條約，規定，規章等文件中，表示一種義務，多用于第三人稱中。The interest shall be divided into five parts, according to the agr

10、eement made by both sides ? ” declared the judge ?（4）用于第一人稱表將來。I shall go to work after I have finished school6、w訂1和would的基本用法.表示意志和意愿。w訂1指現在，would指過去。女口： If you will listen to me,I 11 give you some advice ?(2) . 表示請求、建議， would 比 will 委婉、客氣如: Will (Would ) you please pass me the book?(3) . 表示習慣性動作，“

11、總是”“慣于”， will 指現在， would 指過去。如:Fish will die without water?Every evening, she would sit by the window, deep in thought?.表示功能,意為能或行，如：The machine wont work.(5) . Will 用于表示決心 (可譯成”一定要 , 決心，等”)如:We will never talk about that subject again? 我們決不會再談 論這個話題了。7、would & used to(1) . 表示過去持續的狀態和悄況用 used to; wo

12、uld 不與表示狀態的動詞連 用。如 There used to be a hospital here? / There would be a hospitdl here. ( X)(2) . would常與 often, sometimes, for hours 等表示時間的副詞 (短語)連用。如 We would sit in the yard every evening and listened to his story?(3). used to 強調過去的行為同現在的對比，含有“過去怎樣，而現在卻不這樣了 的含義，如: He will not spend the money on bo

13、oks as he used to?8、need 和 dare(1) .need 表“需要” dare “敢”.只用于否，疑，條件句中 .后接加動詞原形如:一 Need I help you?Yes, please ?You needn t telephone him now.How dare you talk to the teacher like that?The girl dare not go out alone at night?(2) . 做實意動詞后加不定式。如: We need to tell him the news ?You don* t needto tell him t

14、he news ?Do the flowers need watering?I didi t dare to tellyou the truth ?Would you dare to catch the snake with your hand?The boy dares to do anything he likes.專題練習1 Will Mr Wang offera hand?HeA. can2. Peteryet.be glad to.B? mustA. must B ? mayHe never refused our requestC. may D? shouldcome with u

15、s tonight, but he isn t very sureC? can D. will3 Write to me when you get home.A. I mustB? I should C. I willD? I canyou4. CouldI borrow your dictionary?A. might B. willC? can D. should5. When he was there, he.go to that coffee shopat the cornerafter workevery day.A. wouldB? shouldC? hadbetterD? mig

16、ht6. Whyit rain now? Igo to the concert at7. - 一 What a pity!A. can; might not Bshould; needn t Cmust: can* t D. need;mustn t7.What do you think of your nephew?Hebe very naughty but at the same time you _ help liking him.A. will; willB. won t ; can* tC? may;may D? can; can* t8. Keep up a good state

17、of mind even if you fail plenty oftimes ?D.A. must B? will C? canshould9. If you _ wait a moment, I will go and find our manager ?D?A. can B. should C? willbe true ?must10. Don t believe him. His storyA. mustn t B. neednA t11.fresh air, but the windowC? shouldn tD. may notWe need someopen.I help you

18、?A. didnt; Will B. shant; Need C? mustn t; May D. wont; Shall、悄態動詞表推測用法- ）可以用來表示推測的情態動詞以及把握性大小1. must 只用于肯定句，表示較有把握的推測，意為“準是，一定”- Ive had no sleep for 48 hours. You must be verytired.2. con 也表示較有把握的推測，多用于否定句和疑問句。用于否定句，意為 “不可能，一定不（是）”。在疑問句中，含有懷疑或疑問的意味，意為“會（是）?”例如： Can the news be true? Who can it be?

19、 He can thave seen her there.3. may表示對現在把握不大的推測，不用在疑問句中，意為“也許，可能”。如：Dont play with the knife. You may cut yourself.不要玩小刀，你可能 會傷了自己。4. could, might 也可表示把握不大的推測，常用在過去時態中；但在某些 場合下，為了使語氣更緩和、更委婉，常用 could, might 代替 can, mayo 如：You may/might/could be very tired.你可能很累吧！5. can 當用于肯定句表示可能性時，表示的是客觀上存在的可能性，意為有時

20、可能會 . ”，其時間意義寬泛不具體。例如 :?Smoking can causecancer.?Anyone can Even experienced teachers can make mistakes.make mistakes.6. should 用于肯定句中表示可能性，意為“很可能，應該”，指按常理推 測。如：They left yesterday. They should be home by now.( 二 ) 悄態動詞表示推測的句式1. 情態動詞 +動詞原形： 表示對現在或將來的情況的推測，此時動詞通常為系動 詞。I dont know where she is, she ma

21、y be in Wuhan.2. 情態動詞 +動詞現在進行時 (be doing): 表示對現在 / 將來正在進行的情況進行 推 測。At this moment, our teacher must be correcting our exam papers.3.情態動詞 +動詞完成時 (have done):表示對過去情況的推測。She has gone to America. He can* t/couldn t have seen her there.The road is wet. It must have rained last night.4. 情態動詞 +動詞的現在完成進行時 (

22、have been doing):表示對過去某段時間發生情況的推 測。Your mother must have been looking for you.( 三 ) 悄態動詞表推測時的反義疑問句情態動詞表推測時的反義疑問句和情態動詞無關，與推測的時間和惜態動詞 后的動詞有關。1. 悄態動詞 +動詞原形：用一般現在時反問： She can t be at home now, isn t she?2. 情態動詞 +動詞現在進行時 (be doing): 用對現在進行時反問：Tom must be sleeping now, isn* t he?3?情態動詞+動詞完成時(have done):有明確表過去的時間狀語(從句), 用一般過去時反問；沒有表過去的時間狀語，用現在完成時形反問：You cant have been to Beijing before, have you?They must have been to the Great Wall, haven- t they?They must have been to the Great Wall last summer, werent they?It must have rained last night, didnt it?You must have been asleep w