外研版八年级下册英语专题-祈使句和情态动词讲解及练习（无答案）.docx

1、1 祈使句和情态动词讲解祈使句和情态动词讲解 课前练习课前练习： 单选题 1. _ on the grass, or it will “cry”. A. To walk B. Not to walk C. Walk D. Dont walk 2. _ swim in the river alone, Karen. Its too dangerous. A. Not B. Dont C. Doesnt 3. _ along this street, and you can find the hotel on your right, next to the market. A. Walk B. T

2、o walk C. Walks D. Walking 4. Daniel，_ play with the mobile phone while youre walking in the street. A. dont B. doesnt C. wont D. cant 5. Someone is knocking at the door._ it be Venis? No， it _be her. She left for New York this morning. A. Must； cant B. Can； cant C. Could； mustnt D. Must； may not 6.

3、 You _be happy with the strong public support youve received. Yes，youre right. Im really excited. A. may B. can C. must D. need 7. It is cold in the room. They _have turned off the heating. 2 A. must B. ought to C. should D. could 8. You _return the book now. You can keep it till next week if you li

4、ke. A. cant B. mustnt C. neednt D. may not 9. Johnny，you _play with the knife，or you _hurt yourself. A. wont ；cant B. mustnt ；may C. shouldnt ；must D. cant ；shouldnt 知识点讲解知识点讲解 一一、祈使句祈使句 概念：概念： 用来表示请求、命令、叮嘱、建议等的句子叫祈使句。祈使句的谓语动词用原形，句 子没有主语，句末使用感叹号或者句号。 例如：Open the door quickly！ 快打开门！ 【用法讲解】【用法讲解】 1. 祈

5、使句的肯定句。祈使句的肯定句。 1）以系动词）以系动词 be 开头的祈使句。开头的祈使句。 这种句式的结构是：Be 动词其它成分(形容词、名词或介词短语等) 例如：Be quiet / quick! Be a good student! Be careful when crossing the street. 2）以实义动词开头的祈使句。）以实义动词开头的祈使句。 3 这种祈使句的常用结构为：行为动词原形其它成分。 例如：Come in, please！请进！ Stand up, please. = Please stand up. 请起立。 3）let 句型。句型。 这种祈使句的常用结构为：

6、Lets / let us+动词原形；或者是 Let + 宾语+其他。 Lets play football！ 我们一起踢足球吧！ Let me help you. 让我来帮你。 2. 祈使句的否定句。祈使句的否定句。 1）Dont + 动词原形。动词原形。 Dont be careless. 别粗心。 Dont be late again. 不要再迟到。 Dont let them play with fire. 别让他们玩火。 Dont look at your books. 不要看书。 2）Let 引起的祈使句的否定形式。引起的祈使句的否定形式。 a. Lets ( Let sb. )

7、+ not + 动词原形。动词原形。 Lets not say anything about it. 对于这件事，咱们什么也别说。 Let them not play with fire. 别让他们玩火。 b. Dont+ let+宾语宾语+动词原形动词原形+其他。其他。 Dont let Jim do that. 别让吉姆做那事。 Dont let us go, please. 请不要让我们走。 3）在公共场合的提示语中，否定祈使句常用“）在公共场合的提示语中，否定祈使句常用“No名词名词 / V-ing 形式形式”结构，表示“禁”结构，表示“禁 止做某事” 。止做某事” 。 4 例如： N

8、O PHOTOS! 禁止拍照！ No parking! 禁止停车！ 3.祈使句的反意疑问句。祈使句的反意疑问句。 1）肯定祈使句的反意疑问句反问部分用）肯定祈使句的反意疑问句反问部分用 will you 或或 wont you。 Please open the door, will/ wont you? 请把门打开，好吗？ Be sure to write to us, will/ wont you? 你一定要给我们写信，好吗？ 2）否定祈使句的反意疑问句反问部分只用）否定祈使句的反意疑问句反问部分只用 will you。 Dont be late again, will you? 别再迟到了

9、，行不行？ Dont smoke in the meeting room, will you? 不要在会议室抽烟，好吗？ 3）以）以 lets 开头的祈使句反意疑问句反问部分用开头的祈使句反意疑问句反问部分用 shall we。 Lets turn on the TV, shall we? 我们把电视打开，好吗？ 以 let us 开头的祈使句的反意疑问句的反问部分应为 will you 或 wont you. 例如：Let us stay here, will/ wont you? 请（你）让我们留在这好吗？ 4. 祈使句的回答。祈使句的回答。 祈使句的动作通常是表示将来发生的动作，所以回答

10、祈使句时，一般用 will 或 wont。 在回答具有否定意义的祈使句时，要注意两点： 1) 形式一致：即 Yes 与 will 保持一致；No 与 wont 保持一致。 2) 意思相反：即 Yes 是 “不”的意思；No 是“是”的意思。 在回答时，要注意分析上下文语境中所提供的条件。例如： Dont go out, please. Its raining heavily outside. 请不要出去。外面雨下得很大。 Yes, I will. I have to meet my brother at the airport. 5 不行，我得去机场接我弟弟 5. 祈使句使用时应注意的问题。祈

11、使句使用时应注意的问题。 1）在表达请求或劝告时，有时为了表示委婉的语气，可以在句首或句末）在表达请求或劝告时，有时为了表示委婉的语气，可以在句首或句末 please，但是，但是 如果如果 please 加在句末，应用逗号将其与前面的部分隔开。加在句末，应用逗号将其与前面的部分隔开。 例如：Sit down, please. 请坐。 Please look after the twins. 请照顾一下双胞胎。 2）在意思比较明显的情况下，可以把谓语动词省略。）在意思比较明显的情况下，可以把谓语动词省略。 例如：This way, please. 请这边走。 3）有时为了加强语气，可以在动词前使

12、用）有时为了加强语气，可以在动词前使用 do. 例如：Do be careful！一定要小心！ 4）有时为了强调对方，也可加上主语）有时为了强调对方，也可加上主语 you，人名或，人名或 everybody, anybody 等不定代词。等不定代词。 例如：You sweep the floor and I clean the window. 你来扫地我来擦窗户。 Stand up, everybody. 请大家起立。 5）有时为了明确向谁提出请求或发出命令，可加称呼语，但称呼语要与句子用逗号隔）有时为了明确向谁提出请求或发出命令，可加称呼语，但称呼语要与句子用逗号隔 开。开。 例如：Put

13、the shirt on the bed, Jim. 吉姆，把衬衫放床上。 课堂练习课堂练习 . 单项选择。单项选择。 6 1. _ with fire. Its very dangerous. A. Playing B. Play C. Dont play D. Doesnt play 2Dont _ the radio. The baby is sleeping. A. turn off B. turn on C. turn over D. turn down 3. _ hard and youll make progress in English. A. Work B. To work

14、C. Working D. Worked 4. _ worried about me Mom. Ive grown up. A. Dont B. Dont be C. Not D. Not be 5. _ late again, Bill! A. Dont to be B. Dont be C. Not be D. Be not 6. _ cross the road until（直到）the traffic lights turn green. A. Not B. Wont C. Doesnt D. Dont 7. Please help me carry it, _? A. will I

15、B. will you C. shall I D. shall we 8. Dont make so much noise, _? A. will you B. wont you C. shall we D. do you 9. Kate, _ your homework here tomorrow. A. bring B. brings C. to bring D. bringing 10. _ me the truth, or Ill be angry. A. Telling B. To tell C. Told D. Tell 7 . 将以下祈使句改为否定式。将以下祈使句改为否定式。 1

16、. Come here early. _ 2. Ask him. _ 3. Please wait for her. _ 4. Read the book carefully. _ 5. Sit under the tree, please. _ 6. Lets go there together. _ . 句型转换。句型转换。 1. Will you please read it again more slowly? （改为祈使句） _ _ again more slowly, please. 2. Lets watch the sports games. （改为反意疑问句） Lets wa

17、tch the sports games, _ _? 3. Please sit next to Nancy.（改为否定句） _ _ next to Nancy. 4. Dont forget to turn off（关掉）the lights, please.（改为反意疑问句） Dont forget to turn off the lights, _ _? 8 5. Come to my house tomorrow.（改为反意疑问句） Come to my house tomorrow, _ _? 9 二、二、情态动词情态动词 概念概念： 情态动词有具体的词义，但也同助动词一样，需要与其

18、他词语一起构成句子的谓语， 另外情态动词没有人称和数的变化，情态动词后必须跟动词原形。 【用法讲解】【用法讲解】 I、常见情态动词的用法、常见情态动词的用法 一、一、can 的用法：的用法： (1) 表示能力。 表示能力时一般译为“能、 会”， 即有某种能力， 尤其是生来具备的能力， 此时 may 和 must 均不可代替它。例如： She can swim fast, but I cant. 她能游得很快，但我不能。 I can see with my eyes. 我用眼睛看。 (2) 表示许可，常在口语中。例如： You can use my dictionary. 你可以用我的字典。 (

19、3) 表示推测。 表示推测时， 意为“可能”， 常用于否定句和疑问句中， 此时 cant 译为“不 可能”。 例如： Can the news be true? 这个消息会是真的吗？ Can the man be our teacher?那个人有可能是我们老师吗？ No, he cant be our teacher. Our teacher is on a visit to the Great Wall. 不可能。咱们老师正在游览长城呢。 二、二、could 的用法：的用法： 10 (1) can 的过去式，意为“能、 会”，表示过去的能力。例如： He could write poems

20、when he was 10. 他十岁时就会写诗。 (2) could 在疑问句中，表示委婉的语气，此时 could 没有过去式的意思。例如： Could you do me a favour? 你能帮我个忙吗？ Could I use your pen? 我能用一下你的钢笔吗? Yes, you can.可以。 三、三、may 的用法：的用法： (1) 表示请求、许可，比 can 正式。例如： May I borrow your bike? 我可以借你的自行车吗？ You may go home now. 现在你可以回家了。 (2) 表示推测，谈论可能性，意为“可能， 或许”，一般用于肯定句

21、中。 例如： It may rain tomorrow. 明天可能会下雨。 She may be at home. 她可能在家呢. (3) may 的过去式为 might，表示推测时，可能性低于 may。 例如： He is away from school. He might be sick. 他离开学校了，可能是他生病了。 (4) 表示希望、祈求、祝愿，常可译为“祝愿”。通常是用 may +主+动词。 例如： May you have a good time. 祝你过得愉快。 May you be happy! 祝你幸福！ May you succeed! 祝你成功！ 四、四、must 的

22、用法：的用法： 11 (1) must 表示主观看法，意为“必须、一定”。 例如： You must stay here until I come back. 在我回来之前你必须待在这儿。 Must I hand in my homework right now? 我必须现在交作业吗？ (2) 其否定形式 mustnt 表示“一定不要” “千万别”“禁止，不许”。例如： You mustnt play with fire. 你不许玩火。 You mustnt be late. 你一定不要迟到。 (3) 对 must 引导的疑问句，肯定回答为 must，否定回答为 neednt 或 dont h

23、ave to。例如： Must I finish my homework? 我现在必须完成作业吗？ No, you neednt.不，你不必。 (4) must 表示有把握的推测，用于肯定句。例如： The light is on, so he must be at home now. 灯亮着，他现在肯定在家。 注意：反意疑问句的构成形式： 当 must 表示肯定的判断、推测时，其反意疑问句要用实际问句的助动词来构成。例如： She must have seen the film before, hasnt she? (注意反意疑问句的后半部分) You must have met uncle

24、 Wang in the shop yesterday, didnt you? (注意反意疑问句的后半部 分) 五、五、need 的用法：的用法： (1) need 表示需要、必须，主要用于否定句和疑问句中，其否定形式为 neednt，意为“没 有必要， 不必”。 用 need 提问时， 肯定回答为 must， 否定回答为 neednt 或 dont have to。 例如： Need I stay here any longer? 我还有必要留在这儿吗？ Yes, you must. 是的。 12 No, you neednt /dont have to. 不， 你不必。 (2) need

25、还可以作实义动词，此时有人称、数和时态的变化，如果是人作主语，后边多 接动词不定式。例如： I need to do it right now. 我需要马上做这件事。 He needs to learn more about the girl.他需要多了解那个女孩。 如果是物作主语，一般用 need doing 与 need to be done。这种情况应注意两点： 1) 主动形式的动名词 doing 具有被动的含义； 2) 该动名词可以改为其动词不定式的被动形式而句子的意义不变。例如： The door needs painting. = The door needs to be pain

26、ted. 那扇门需要油漆一下。 Your car needs mending. = Your car needs to be repaired. 你的车需要维修了。 六、六、shall 的用法：的用法： shall 表示征求对方意见（多用于第一、三人称） ，例如： Shall we go out for a walk? 我们出去散步好吗？ 七、七、should 的用法：的用法： (1) should 意为“应该”，可表示劝告、建议、义务、责任等。 例如： We should protect the environment. 我们应该保护环境。 (2) should have done 表示对过

27、去动作的责备、批评。例如： You should have finished your homework. 你应该已经完成作业了。 （事实上你没有完成。 ） 八、八、will 的用法：的用法： will 表示意愿、意志、打算，可用于多种人称。例如： 13 I will help you if Im free this afternoon.今天下午如果我有空，我就会帮你。 II、情态动词易混点归纳、情态动词易混点归纳 易混点一：易混点一： can 和和 be able to 两者表示能力时用法相同，但 can 只有原形“can”和过去式“could”两种形式，在其他时 态中要用 be able

28、to 来表示。另外 be able to 常常指经过努力，花费了时间和劳力之后才能 做到某事。例如： Jim cant speak English.吉姆不会说英语。 He could speak English at the age of 5. 他五岁时 就会说英语。 Well be able to see him next week.下星期我们将会见到他。 He has been able to drive. 他已经会开车了。 Im sure youll be able to finish it quickly.我相信你能迅速地完成。 We were able to reach the to

29、p of the mountain at noon.我们能在中午到达山顶。 易混点二：易混点二：can 和和 may 1. can 和 may 均可用来征求意见或许可，意为“可以”， 一般可互换使用。例如： Can / May I help you? 我能帮助你吗？ 2. can 和 may 表示可能性时的区别： 1) 在肯定句中用 might，may，must，不用 can。 2) 在疑问句中表示推测用 can，不用 might，may，must。 3) 在否定句中用 cant（不可能） ， 不用 may， must。 例如： She may be in the classroom. 她可能

30、在教室里。 14 Where can they be now? 他们现在可能在哪儿？ That cant be true. 那不可能是真的。 易混点三：易混点三：cant 和和 mustnt 1. cant 根据其基本用法可译为： (1) 不会。例如：I cant speak English. 我不会说英语。 (2) 不能。例如：We cant do it now because its too dark.天太黑了，我们现在干不了。 (3) 否定句中表示推测，意为“不可能”。例如： The man cant be our teacher because he is much younger t

31、han our teacher. 那个人不可能是咱们老师，他年轻得多。 2. mustnt 意为“禁止、不许”， 用来表达命令，表示强烈的语气。 例如： You mustnt play football in the street. Its too dangerous.你不可以在街上踢足球， 太危险了。 易混点四：易混点四：must 和和 have to 1. must 侧重于个人意志和主观上的必要。have to 侧重于客观上的必要，可用于现在时、 过去时和将来时。例如： I know I must study hard. 我知道我必须努力学习。 My brother was very il

32、l, so I had to call the doctor in the mid-night. 我弟弟病得厉害， 我只得半夜里把医生请来。 I havent got any money with me, so Ill have to borrow some from my friend. 我身上没带钱，只好向朋友借点了。 He said they must work hard.他说他们必须努力工作。 2. have to 可以用于多种时态；而 must 只用于一般现在或将来。例如： 15 The composition is due to hand in this morning, so I

33、 had to finish it last night. 作文今天早晨到期，因此我不得不昨天晚上完成。 课堂练习：课堂练习： 选择填空。选择填空。 1. I think Miss Gao must be in the library. She said she would go there. No. She _ be there, I have just been there. A .cant B. mustnt C. neednt D. wouldnt 2. _ I borrow your MP3? Sure. Here you are. A. May B. Should C. Must

34、D. Would 3. May I go to the cinema, mum? Certainly, but you _ be back by 11 oclock. A. can B. may C. must D. need 4. You _ get there by bus. A. dont need B. neednt to C. dont need to D. need dont to 5. You _ worry about me. Its nothing serious. A. cant B. mustnt C. neednt D. wont 6. Excuse me. Is th

35、is the right way to the Summer Please? 16 Sorry, Im not sure. But it _ be. A. might B. mustnt C. cant D. must 7. The man in the office _ be Mr. Black, because he went home just now. A. mustnt B. may not C. cant D. neednt 8. Can you go surfing with us this afternoon? Id like to, but I _ look after my

36、 sister at home , because my mother is ill. A. need B. must C. have to D. should 9. May I take this book out of the reading room? _. Please read it here. A. Certainly B. No, you neednt C. No, you mustnt D. No, you may not 10. Could I use your dictionary? Of course, you _. A. can B. should C. could D

37、. must 11. Whose pencil box is this? It _ be Toms. It has his name on it. A. must B. may C. might D. cant 12. you sing the song Where Are You Going, Daddy? Yes. Its easy. A. Can B. May C. Must 13. All passengers _ go through safety check before they take a plane.（ A. can B. may C. must D. ought 17 课

38、后练习课后练习： 一一. 用括号内所给动词的适当形式填空。用括号内所给动词的适当形式填空。 1. Its an important meeting. _ (not, be)late. 2. _ (not, make) any noise! Your mother is sleeping. 3. _ (not, speak) with your mouth full of food and _ (be) polite. 4. _ ( not, talk) and _ (read) aloud. 5. _ (not, leave) your homework for tomorrow, Larry

39、. 6. _ (look) out! A car is coming. 7. _ (give) us ten years and just see what our country will be like. 8. _ (not, let) the baby cry. 9. Wear more clothes or you _ (catch) a cold. 10. Lets _ (not, say) anything about it. 二二、选用、选用 can, may, must, cant, mustnt, neednt, should, could 填空。填空。 1. There i

40、s air around us, though we _ see it. 2. Your mother is getting better and better. You _ worry about her. 3. You _ play football in the busy street. 4. “_ it be true ?” “Yes. It _ be true indeed.” 18 5. Tom _ come to the party tonight, but Im not sure. 6. _ you please fetch me some water for me? 7. Y

41、oung trees _ be planted in spring. 8. “Must we hand in our exercise books today?” “Yes, you _.” “No, you _.” 9. “May I take this magazine out of the reading-room?” “No, you _.” 10. Please speak a little louder so that I _ hear you. 三、完形填空完形填空。 通读下面短文，掌握其大意，然后在每小题所给的四个选项中，选出一个最佳答 案，并将其字母编号填写在题前括号内。 M

42、r Black loved his daughter Helen very much. Every day he spent all of his free time 1 with her. One night，he had much work to do， 2 couldnt play with his daughter. In order to keep her 3 ，he found a map of the world in the magazine and cut it into pieces. When he 4 ，Helen came running to him and was

43、 ready to play. Mr Black said he had 5 time to play right now. He told the girl to put the pieces of paper back together to a map of the world， and then they both could play. About half an hour later， Helen came to her father and said， “Okay， its finished. Can we play now?” Mr Black was surprised，an

44、d said，“Thats 6 .Lets go and see.” And sure enough，there was the picture of the world；all put together，every 7 in its place. Mr Black said， “Thats surprising! 8 did you do that?” Helen said， “It was 9 .On the back of the page was a picture of a 10 .When I put the man together， the whole world fell i

45、nto place.” ( )1.A.working B.running C.walking D.playing 19 ( )2.A.or B.but C.and D.then ( )3.A.sleepy B.busy C.free D.warm ( )4.A.left home B.went to the office C.left the office D.got home ( )5.A.no B.enough C.much D.some ( )6.A.possible B.right C.impossible D.wrong ( )7.A.map B.picture C.piece D.

46、page ( )8.A.Why B.How C.When D.Where ( )9.A.simple B.different C.difficult D.hard ( )10.A.woman B.man C.girl D.boy 四、短文填空 请用适当的词完成下面的短文，并把所缺单词填写在指定的位置上。每空只能填写一个形 式正确、意义相符的单词。 Helping other people is a good virtue (美德) in China. But nowadays， the good virtue is disappearing because of fear. We hope t

47、o be warm-hearted people， but someone will stop 1 .Xiao Ming is a middle school student. One day，Xiao Ming went shopping 2 his mother. Suddenly，he saw a little girl 3 over. He wanted to help the girl 4 ， but his mother 5 him at once and said，“Dont do that，otherwise others will think it was you who k

48、nocked her down.” Another day at home，Xiao Mings mother was 6 with him because he just let the fallen oil bottle be. His mother shouted at him，“Cant you see the fallen 7 ? Why cant you pick it up?” But Xiao Ming said to his mother，“ 8 I picked the bottle up，you would think that I did it.” 20 I disagree with what the moth