Unit 2 Home Sweet Home 语法知识精讲及练习 2026-2027学年人教版八年级英语上册

该初中英语知识清单聚焦人教版八年级上册Unit 2情态动词can/could表请求与许可的语法体系。从请求（委婉礼貌与日常随意句式及答语）到许可（征求许可的句式与答语），结合四大通用规则和中考高频考点，构建从基础用法到实际应用的学习支架。 知识链路按“请求-许可-规则-考点-练习”逻辑展开，通过表格对比不同语气的句式与例句，配套单选、填空、改写及情景对话练习。习题贴近生活情境，参考答案解析具体，助力学生通过辨析can/could语气差异提升思维品质，结合中考考点强化语言能力，培养科学学习策略。

人教版八年级上册英语 语法知识精讲与配套练习 Unit 2 Home Sweet Home 📌 本单元语法焦点：情态动词 can / could 表请求与许可 📖 语法知识详解 一、can / could 表请求（Requests） 向他人提出请求、请对方帮忙做某事。 语气 句式 例句 委婉礼貌（长辈/陌生人） Could you please + 动词原形? Could you please sweep the floor? 日常随意（家人/朋友） Can you + 动词原形? Can you help me hang up the photos? 标配答语（肯定） Sure / Of course / No problem. — Could you help me? — Sure! 标配答语（否定） Sorry, I can't. / I have to... — Can you do it? — Sorry, I can't. 🎯 中考考点：中考高频考点：① can/could 后永远接动词原形（❌ Can you to help me? → ✅ Can you help me?）；② could 表请求时不是can的过去时，而是表示更委婉的语气；③ 否定答语常用 Sorry, I can't. 而不用 couldn't。 二、can / could 表许可（Permission） 向别人征求许可，允许自己做某事。 语气 句式 例句 委婉礼貌 Could I + 动词原形? Could I hang out with friends after lunch? 日常口语化 Can I + 动词原形? Can I put some flowers on the table? 肯定答语 Yes, you can. — Can I go now? — Yes, you can. 否定答语 Sorry, you have to... — Could I go out? — Sorry, you have to finish homework first. 四大通用规则： ① 后只能接动词原形，不变形、不加 to ② 无人称变化：he/she/it 后面依旧用 can/could ③ 否定形式：can't = can not; couldn't = could not ④ could 比 can 语气更礼貌委婉 🎯 中考考点：中考高频考点：① can/could 后接动词原形是铁律；② 区分 can（能力/可能性）与 can（请求/许可）的不同语境含义；③ 回答 Could you...? 用 can 不用 could。 ✏️ 配套练习题 一、单项选择（10题，每题1分，共10分） 1. — Could you please ______ the floor? A. to sweep B. sweep C. sweeping — Sure, I'll do it right away. 2. — ______ I use your dictionary? A. Must B. Should C. Could — Yes, you can. 3. — Could you please help me with my homework? — ______ A. Sorry, I can't. I have to go now. B. Sorry, I couldn't. I have to go now. C. Yes, I could. 4. — Can I ______ TV now, Mom? A. to watch B. watch C. watching — No, you have to finish your homework first. 5. ______ you please pass me the salt? A. Do B. Are C. Could — Here you are. 6. — Could I hang out with my friends after dinner? — ______ A. Yes, you could. B. Yes, you can. C. No, you don't. 7. — Can you please ______ me clean the room? A. help B. to help C. helping — Of course! 8. — Could I go to the movies tonight? — ______ A. Sorry, you can. B. Sorry, you have to stay at home. C. Yes, you couldn't. 9. In the sentence "Can you pass me the book?", "can" expresses ______. A. ability B. a request C. possibility 10. Which is the most polite way to ask a stranger for help? A. Can you help me? B. Could you please help me? C. You must help me. 二、用 can / can't / could / couldn't 填空（10题，每题1分，共10分） 1. — ______ you please turn down the music? It's too loud. — Sure, sorry about that. 2. I ______ speak English well when I was five. I started learning at six. 3. — ______ I go to the bathroom, please? — Yes, you ______. 4. She ______ be at home now. Her car is still in the driveway. 5. — ______ you help me carry these bags? — Sorry, I ______. I have a backache. 6. When I was young, I ______ run very fast, but now I can't. 7. — ______ I borrow your pen for a minute? — Of course. Here you are. 8. He ______ find his keys anywhere this morning. He was very worried. 9. You ______ smoke in this building. It's against the rules. 10. — ______ you please repeat that? I didn't hear you clearly. — Certainly. 三、改写句子（5题，每题2分，共10分） 1. Can you help me? (改为更礼貌的请求) → ______ ______ please help me? 2. Could I go out now? (作肯定回答) → Yes, ______ ______. 3. She can speak French. (改为一般疑问句) → ______ she ______ French? 4. Could you please close the window? (作否定回答) → Sorry, ______ ______. I'm too far away. 5. He can play the piano. (用 could 改写，表示过去的能力) → He ______ ______ the piano when he was young. 四、情景对话填空（10题，每题1分，共10分） A: Mom, (1)______ I go to the park with my friends this afternoon? B: (2)______ you please finish your homework first? A: But Mom, I (3)______ do my homework after dinner. All my friends are going! B: Hmm, okay. (4)______ you be back before 6:00 p.m.? A: Yes, I (5)______. I promise! B: And (6)______ you please call me if your plans change? A: Sure, Mom. (7)______ I borrow your phone? Mine is dead. B: Here you are. And (8)______ you be careful crossing the street? A: Of course, Mom! I always am. (9)______ I take some snacks with me? B: Yes, you (10)______. There are some cookies in the kitchen. 📝 参考答案 一、单项选择 1. B （Could you please 后接动词原形，sweep the floor 扫地。） 2. C （征求许可用 Could I...? 答语用 Yes, you can. 符合语法规则。） 3. A （Could you...? 的否定回答用 Sorry, I can't. 而非 couldn't；could 表请求时不是过去时。） 4. B （Can I 后接动词原形 watch，情态动词后永远不加 to。） 5. C （Could you please...? 用于礼貌请求，比 Can you 更委婉。） 6. B （Could I...? 表征求许可，肯定回答用 Yes, you can. 不用 could。） 7. A （Can you please help me... 后接动词原形 help。） 8. B （否定回答用 Sorry, you have to... 说明不能去的原因。） 9. B （在此语境中 Can you pass me... 是请求对方递书，表请求而非能力。） 10. B （向陌生人求助，用 Could you please... 最礼貌委婉。） 二、用 can / can't / could / couldn't 填空 1. Could （Could you please...? 礼貌请求对方调低音量。） 2. couldn't （when I was five 提示过去时，couldn't 表示过去不能。） 3. Can; can （Can I...? 征求许可；肯定回答用 Yes, you can.） 4. can （can 表可能性推测，她现在可能在家。） 5. Can; can't （Can you...? 请求帮助；Sorry, I can't 礼貌拒绝。） 6. could （when I was young 提示过去能力，could 表示过去能。） 7. Could （Could I...? 委婉征求许可借笔。） 8. couldn't （this morning 提示过去时，couldn't 表示找不到。） 9. can't （can't 表禁止，大楼内禁止吸烟。） 10. Could （Could you please...? 礼貌请求对方重复一遍。） 三、改写句子 1. Could you please help me? （用 Could you please + 动词原形 表更礼貌的请求。） 2. Yes, you can. （Could I...? 的肯定回答用 can，不用 could。） 3. Can she speak French? （含 can 的陈述句改一般疑问句，将 can 提前。） 4. Sorry, I can't. （Could you please...? 的否定回答用 can't。） 5. He could play the piano when he was young. （could 是 can 的过去式，表过去的能力。） 四、情景对话填空 1. Could （Could I...? 向妈妈征求许可去公园。） 2. Could （Could you please...? 妈妈请求孩子先完成作业。） 3. can （can 表能力/可能性，表示晚饭后可以做作业。） 4. Can （Can you be back...? 询问能否在6点前回来。） 5. can （肯定回答 Yes, I can. 表示能做到。） 6. could （Could you please...? 请求对方计划有变时打电话。） 7. Could （Could I...? 委婉借手机，比 Can I 更礼貌。） 8. can （Can you be careful...? 提醒注意安全。） 9. Could （Could I...? 再次征求许可带零食。） 10. can （肯定回答 Yes, you can. 同意请求。） 学科网（北京）股份有限公司 $