Unit 4 Helping out 情态动词（2） (语法讲解+分层精练）-2025-2026学年外研版八年级英语下册

Unit 4 Helping out （情态动词Ⅱ） (语法讲解+分层精练） 目 录 一、语法讲解 1 （一）may/might 表示“可能性”（推测） 1 （二）may/might 表示“许可”（请求与允许） 2 二、30道中考题型练习题 2 （一）单项选择（20题） 2 （二）按要求完成句子（10题） 4 一、语法讲解 （一）may/might 表示“可能性”（推测） 用于对现在或将来发生的事情进行不确定的推测。 情态动词 可能性程度 释义 常用句型 may 大概 50% 可能，也许 肯定句：主语 + may + 动词原形 might 大概 30-40% 可能，也许 否定句：主语 + may not/might not + 动词原形 用法要点： 1.语气强弱：may 表示的可能性比 might 要大一些。might 不仅可以是 may 的过去式，还可以用来表示更加不确定或语气更委婉的推测 。 2.无人称变化：情态动词后面跟动词原形，且不受主语人称和数的影响（He may come；不能说 He mays come）。 3.否定形式：表示“可能不”时，直接在后面加 not（may not / might not）。 例句对比： 1.The girl may be a tour guide.（那个女孩可能是一名导游。—— 把握较大） 2.He might apply for the position.（他也许会申请这个职位。—— 把握较小，只是一种可能性） 3.She may not be a teacher.（她可能不是老师。） （二）may/might 表示“许可”（请求与允许） 通常用于请求别人允许自己做某事，或者允许别人做某事 。 用法 例句 说明 请求许可 May I come in?（我可以进来吗？） might 语气更委婉、更礼貌、更正式，但不如 may 常用。 给予许可 You may go home now.（你现在可以回家了。） 通常只用 may，不用 might。 禁止（正式） Visitors may not take photos.（参观者禁止拍照。） 表示“不可以”。 易错点：在口语中回答 May I... 的提问时，肯定回答常用 Yes, you may. 或 Sure.；否定回答常用 No, you mustn't.（语气强，禁止）或 No, you can't.，较少用 may not 。 二、30道中考题型练习题 （一）单项选择（20题） 1. — Whose book is this? — It ______ be Mary's. She was reading it just now. A. can't B. must C. might D. need 2. — Where are you going this weekend? — I'm not sure. I ______ go to the beach with my parents. A. must B. should C. might D. can 3. You ______ smoke here. Look at the sign "No Smoking". A. may B. mustn't C. might D. needn't 4. — ______ I use your dictionary? — Of course you can. Here you are. A. Must B. May C. Should D. Need 5. He ______ be at home. The light is off. A. must B. can C. may not D. mustn't 6. I thought you ______ like something to read, so I brought you some books. A. may B. might C. must D. will 7. The girl in the classroom ______ be Sarah. She has gone to the library. A. may B. must C. can't D. needn't 8. — Is Tom coming by train? — He ______ drive his car. I'm not sure. A. can't B. may C. must D. should 9. — Mom, ______ I play computer games now? — Sorry, you must finish your homework first. A. may B. must C. should D. will 10. Take an umbrella with you. It ______ rain later. A. may B. must C. need D. can 11. He ______ be over sixty. His father is only fifty-eight. A. can't B. mustn't C. may not D. shouldn't 12. — Excuse me. Is this the right way to the museum? — Sorry, I'm not sure. It ______ be. A. must B. might C. can't D. mustn't 13. You ______ tell lies. It's not polite. A. may not B. mustn't C. needn't D. might not 14. — There is somebody knocking at the door. — Who ______ it be at this late hour? A. must B. may C. can D. should 15. She ______ know the answer. Let's ask her. A. may B. can C. must D. should 16. — ______ you succeed! — Thank you. A. May B. Must C. Can D. Should 17. I'm not sure, but he ______ come to the party tonight. A. may B. must C. need D. shall 18. The sweater ______ belong to Jim. It's much too large for him. A. mustn't B. can't C. needn't D. may not 19. — May I take this book out of the reading room? — No, you ______. You read it here. A. may not B. mustn't C. needn't D. couldn't 20. Don't play with the knife. You ______ hurt yourself. A. may B. should C. have to D. need （二）按要求完成句子（10题） 1. He is at home today.（用 might 改写为表推测的句子） He ______ ______ at home today. 2. You may be right.（改为否定句） You ______ ______ right. 3. Can I use your phone?（写出同义句） ______ I use your phone? 4. It will be sunny tomorrow. It will be cloudy tomorrow.（用 may 合并为一句） It ______ be sunny or cloudy tomorrow. 5. She is possibly his sister.（用 may 改写） She ______ ______ his sister. 6. You mustn't play football in the street.（改为语气较委婉的否定推测） You ______ ______ play football in the street.（表示可能不被允许） 7. He may not be a doctor. I'm not sure.（写出同义句） He ______ ______ a doctor. I'm not sure. 8. It might rain, so take an umbrella.（改为否定句） It ______ ______ rain, so you needn't take an umbrella. 9. The runners are standing at the starting line. They're ready to run. （填入适当的情态动词） The race ______ start in a minute. 10. — I can't find my keys. — You ______ put them in your jacket pocket.（填入适当的情态动词，表示一种可能） 答案与解析 （一）单项选择 1. B。根据“她刚才还在读”，可以非常有把握地推测“一定是”玛丽的书。 2. C。由 “I‘m not sure” 可知是不确定的推测，所以用 might（可能）。 3. B。根据“No Smoking”标志，是禁止吸烟，mustn’t 表示“禁止”。 4. B。请求对方许可，用 May I... 是最常见的礼貌用语。 5. C。根据“灯关了”推断“他可能不在家”。这是不确定的否定推测，用 may not。注意 mustn't 表示禁止，不表推测。 6. B。主句是 I thought（我原以为），从句要用过去时态与之对应，所以用 might（可能）。 7. C。根据“她已经去图书馆了”可以推断教室里的人“不可能是”Sarah。有把握的否定推测用 can't。 8. B。由 “I‘m not sure” 可知，这是一种不确定的推测，用 may。 9. A。孩子向妈妈请求许可玩电脑游戏，用 May I...。 10. A。“带伞”是因为“可能会”下雨，表示将来的可能性。 11. A。根据“他父亲才58岁”推断，他“不可能”超过60岁。否定推测用 can't。 12. B。由 “I’m not sure” 可知，不确定，表示“可能（是）”，用 might。 13. B。“说谎”是不礼貌的，因此是“禁止”或“绝不能”。mustn't 语气最强。 14. C。在疑问句中表示“可能”推测，常用 can。 15. A。Let's ask her 暗示她“可能”知道，表示一种不确定的推测。 16. A。“May you succeed！” 是固定句型，表示祝愿。 17. A。由 “I'm not sure” 可知是没把握的推测，用 may。 18. B。根据“对他来说太大了”推断这件毛衣“不可能”是吉姆的。有把握的否定推测用 can't。 19. B。May I... 的否定回答，语气强烈的禁止用 mustn't（不可以/绝不能）。 20. A。警告对方玩刀“可能”会伤到自己，表示一种潜在的可能性。 （二）按要求完成句子 1. might be。might + 动词原形。 2. may not be。may 的否定式直接在后面加 not。 3. May。May I... 与 Can I... 都表示请求许可，但 May 更正式。 4. may。may 表示不确定的选择。 5. may be。possibly 与 may be 都表示“可能”。 6. might not。might 语气更委婉，表示可能性更小。 7. might not be。I'm not sure 对应可能性小的 might not。 8. might not。might 的否定式。 9. may/might。比赛“可能”马上开始，基于现场情况的推测。 10. may/might。表示对过去动作的推测，may/might have put 表示“可能已经把……放到了……”。 1 学科网（北京）股份有限公司 $ Unit 4 Helping out （情态动词Ⅱ） (语法讲解+分层精练） 目 录 一、语法讲解 1 （一）may/might 表示“可能性”（推测） 1 （二）may/might 表示“许可”（请求与允许） 2 二、30道中考题型练习题 2 （一）单项选择（20题） 2 （二）按要求完成句子（10题） 4 一、语法讲解 （一）may/might 表示“可能性”（推测） 用于对现在或将来发生的事情进行不确定的推测。 情态动词 可能性程度 释义 常用句型 may 大概 50% 可能，也许 肯定句：主语 + may + 动词原形 might 大概 30-40% 可能，也许 否定句：主语 + may not/might not + 动词原形 用法要点： 1.语气强弱：may 表示的可能性比 might 要大一些。might 不仅可以是 may 的过去式，还可以用来表示更加不确定或语气更委婉的推测 。 2.无人称变化：情态动词后面跟动词原形，且不受主语人称和数的影响（He may come；不能说 He mays come）。 3.否定形式：表示“可能不”时，直接在后面加 not（may not / might not）。 例句对比： 1.The girl may be a tour guide.（那个女孩可能是一名导游。—— 把握较大） 2.He might apply for the position.（他也许会申请这个职位。—— 把握较小，只是一种可能性） 3.She may not be a teacher.（她可能不是老师。） （二）may/might 表示“许可”（请求与允许） 通常用于请求别人允许自己做某事，或者允许别人做某事 。 用法 例句 说明 请求许可 May I come in?（我可以进来吗？） might 语气更委婉、更礼貌、更正式，但不如 may 常用。 给予许可 You may go home now.（你现在可以回家了。） 通常只用 may，不用 might。 禁止（正式） Visitors may not take photos.（参观者禁止拍照。） 表示“不可以”。 易错点：在口语中回答 May I... 的提问时，肯定回答常用 Yes, you may. 或 Sure.；否定回答常用 No, you mustn't.（语气强，禁止）或 No, you can't.，较少用 may not 。 二、30道中考题型练习题 （一）单项选择（20题） 1. — Whose book is this? — It ______ be Mary's. She was reading it just now. A. can't B. must C. might D. need 2. — Where are you going this weekend? — I'm not sure. I ______ go to the beach with my parents. A. must B. should C. might D. can 3. You ______ smoke here. Look at the sign "No Smoking". A. may B. mustn't C. might D. needn't 4. — ______ I use your dictionary? — Of course you can. Here you are. A. Must B. May C. Should D. Need 5. He ______ be at home. The light is off. A. must B. can C. may not D. mustn't 6. I thought you ______ like something to read, so I brought you some books. A. may B. might C. must D. will 7. The girl in the classroom ______ be Sarah. She has gone to the library. A. may B. must C. can't D. needn't 8. — Is Tom coming by train? — He ______ drive his car. I'm not sure. A. can't B. may C. must D. should 9. — Mom, ______ I play computer games now? — Sorry, you must finish your homework first. A. may B. must C. should D. will 10. Take an umbrella with you. It ______ rain later. A. may B. must C. need D. can 11. He ______ be over sixty. His father is only fifty-eight. A. can't B. mustn't C. may not D. shouldn't 12. — Excuse me. Is this the right way to the museum? — Sorry, I'm not sure. It ______ be. A. must B. might C. can't D. mustn't 13. You ______ tell lies. It's not polite. A. may not B. mustn't C. needn't D. might not 14. — There is somebody knocking at the door. — Who ______ it be at this late hour? A. must B. may C. can D. should 15. She ______ know the answer. Let's ask her. A. may B. can C. must D. should 16. — ______ you succeed! — Thank you. A. May B. Must C. Can D. Should 17. I'm not sure, but he ______ come to the party tonight. A. may B. must C. need D. shall 18. The sweater ______ belong to Jim. It's much too large for him. A. mustn't B. can't C. needn't D. may not 19. — May I take this book out of the reading room? — No, you ______. You read it here. A. may not B. mustn't C. needn't D. couldn't 20. Don't play with the knife. You ______ hurt yourself. A. may B. should C. have to D. need （二）按要求完成句子（10题） 1. He is at home today.（用 might 改写为表推测的句子） He ______ ______ at home today. 2. You may be right.（改为否定句） You ______ ______ right. 3. Can I use your phone?（写出同义句） ______ I use your phone? 4. It will be sunny tomorrow. It will be cloudy tomorrow.（用 may 合并为一句） It ______ be sunny or cloudy tomorrow. 5. She is possibly his sister.（用 may 改写） She ______ ______ his sister. 6. You mustn't play football in the street.（改为语气较委婉的否定推测） You ______ ______ play football in the street.（表示可能不被允许） 7. He may not be a doctor. I'm not sure.（写出同义句） He ______ ______ a doctor. I'm not sure. 8. It might rain, so take an umbrella.（改为否定句） It ______ ______ rain, so you needn't take an umbrella. 9. The runners are standing at the starting line. They're ready to run. （填入适当的情态动词） The race ______ start in a minute. 10. — I can't find my keys. — You ______ put them in your jacket pocket.（填入适当的情态动词，表示一种可能） 1 学科网（北京）股份有限公司 $