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2026春外研社版英语八年级下册 Unit 4-6 重点语法归纳
Unit 4 Helping out
语法主题：情态动词 (II) —— 表推测 (Possibility and Deduction)
定义：当我们对某种情况不确定，或者根据已有证据进行推断时，使用表推测的情态动词。本单元主要学习 must, may, might, can, could, can't 在推测时的用法。
考点1 肯定推测
词汇 语气强弱 用法详解与例句
must 最强 (100%) 意为“一定，肯定”。表示有确凿证据或理由做出的肯定判断。
Look at that man! It must be hard for him to carry all the boxes. (看那个人！搬这么多箱子一定很吃力。)
may / might / could 较弱 (20%-50%) 意为“也许，可能”。表示不确定的推测。might/could 比 may 语气更委婉，可能性更小。
That woman looks lost. She might need help. (那个女士看起来迷路了。她可能需要帮助。)
He could be in pain. (他可能很痛。)
考点2 否定推测
表示“不可能”时，使用 can't 或 couldn't，不能用 mustn't。
can't / couldn't: 意为“不可能”。表示有充分理由相信某事不会发生。
It can't be true! (这不可能是真的！)
The man taking a walk can't be Mr. Li. He has gone to Beijing. (那个散步的人不可能是李先生，他去北京了。)
考点3 疑问推测
表示“可能……吗？”或“会是……吗？”，通常使用 can 或 could。
Can this be true (这可能是真的吗？)
Where could he be (他可能会在哪里呢？)
【易错点】mustn't vs can't
1. mustn't 表示“禁止，不允许”，不表示推测。
You mustn't park here. (你不能在这里停车。)
2. can't 表示“不可能”，是 must (肯定) 的反义词。
The news must be true. (肯定是真的) <-> The news can't be true. (不可能是真的)
Unit 4 过关斩将
一、单项选择
1. —Is the man over there Mr. White
—It ________ be him. He has gone to America.
A. must B. can't C. may D. might
2. —Someone is knocking at the door. Who is it
—It ________ be the postman. He usually comes at this time.
A. must B. can't C. need D. shouldn't
3. The notebook on the desk ________ belong to Tom. Look, his name is on it.
A. can't B. mustn't C. must D. need
4. —Where is Betty
—I'm not sure. She ________ be in the library.
A. must B. might C. can't D. need
5. You ________ be serious! He is only a three-year-old boy.
A. can't B. mustn't C. may not D. needn't
二、用所给词的适当形式填空
6. The dictionary ________ (must) be mine. It has my name on it.
7. —Is that red car Mary's
—No, it ________ (can) be hers. Hers is blue.
8. Don't worry. There is a ________ (possible) that he will recover soon.
9. The girl ________ (may) need some help with her heavy bag.
三、短文填空（每空一词）
Helping others makes us happy. Last Sunday, I went to the local hospital to work as a volunteer. At first, I was worried that I 10.________ (can) not do the work well. But the nurses were very kind. They told me that I 11.________ (need) worry. My job was to read books to sick children. When I walked into the room, I saw a little girl crying. She 12.________ (must) be in pain. I went over and gave her a toy bear. "This 13.________ (may) make you feel better," I said. She stopped crying and smiled at me. I realized that a small act of kindness can make a big difference. Some people think volunteering is a waste of time, but it 14.________ (can) be true. It gives us a chance to help people in need. We 15.________ (should) try our best to help others. If everyone offers a helping hand, the world 16.________ (will) be a better place. I'm sure I 17.________ continue to be a volunteer. Helping others is helping 18.________ (my).
Unit 5 Looking into nature
语法主题：宾语从句 (I) —— that, if, whether 引导
定义：在复合句中，作及物动词或介词的宾语的从句叫宾语从句。本单元重点学习由连词 that, if, whether 引导的宾语从句。
考点1 that 引导的宾语从句
当宾语从句是陈述句时，用 that 引导。that 在口语中常省略，不作成分，无词义。
I think (that) nature is amazing. (我认为大自然很神奇。)
Scientists believe (that) dinosaurs lived on Earth long ago. (科学家相信恐龙很久以前生活在地球上。)
考点2 if / whether 引导的宾语从句
当宾语从句是一般疑问句时，用 if 或 whether 引导，意为“是否”。从句必须用陈述语序。
I wonder if / whether it will rain tomorrow. (我想知道明天是否会下雨。)
Can you tell me if / whether he likes science (你能告诉我他是否喜欢科学吗？)
【易错点】只能用 whether 的情况
1. 与 or not 连用时：whether ... or not.
I don't know whether he will come or not.
2. 在介词之后：
I'm thinking about whether we should go.
3. 后接不定式 (to do) 时：
He hasn't decided whether to go there.
【规划变化】时态呼应原则
1. 主句是一般现在时 → 从句根据实际情况使用任何时态。
2. 主句是一般过去时 → 从句必须用相应的过去时态。
3. 特例：如果从句陈述的是客观真理（如地球绕着太阳转），即使主句是过去时，从句仍用一般现在时。
The teacher said that the earth goes around the sun.
Unit 5 过关斩将
一、单项选择
1. I think ________ amber is a key to unlocking the past.
A. what B. that C. if D. who
2. —Do you know ________ there are any new species in the rainforest
—Yes, scientists found some.
A. that B. if C. what D. where
3. She asked me ________ I could help her with the experiment or not.
A. if B. whether C. that D. when
4. The teacher told us that light ________ faster than sound.
A. travel B. traveled C. travels D. traveling
5. We are not sure ________ they will come to visit the museum.
A. whether B. that C. what D. who
二、用所给词的适当形式填空
6. I believe that we ________ (can) protect the environment well.
7. He asked if I ________ (be) interested in plants.
8. Scientists discovered that the earth ________ (go) around the sun.
9. I'm thinking about ________ (whether) to join the science club.
三、短文填空（每空一词）
Nature is full of secrets. For hundreds of years, people believed 10.________ dinosaurs looked like huge lizards. But recent discoveries changed this idea. Scientists found a piece of amber with a dinosaur tail in it. They were surprised to see 11.________ the tail was covered with feathers! This proves that some dinosaurs 12.________ (have) feathers, just like birds. Amber is like a time capsule. It can tell us 13.________ (what) life was like millions of years ago. Scientists hope to find out 14.________ (if) there are more secrets hidden in amber. Many people wonder 15.________ (whether) we can bring dinosaurs back to life. However, most scientists say 16.________ (that) it is impossible now. Wang Wencai was a great scientist. He spent his life studying plants. He discovered many new species. He showed us that if we observe carefully, we 17.________ (will) find the beauty of nature. Do you want to know 18.________ (if) you can be a scientist like him Just keep curious!
Unit 6 Living with nature
语法主题：宾语从句 (II) —— 特殊疑问词引导
定义：当宾语从句是特殊疑问句时，由连接代词（who, whom, whose, what, which）或连接副词（when, where, how, why）引导。
考点1 语序（陈述语序）
宾语从句必须使用陈述语序，即“连接词 + 主语 + 谓语”。
I don't know where he is. (我不知道他在哪里。)
Could you tell me when the train will leave (你能告诉我火车什么时候开吗？)
【规划变化】疑问句变宾语从句步骤
1. 保留疑问词（what, where, how 等）。
2. 改语序：将疑问句的倒装语序（谓语在前）改为陈述语序（主语在前）。
Where is he → ... where he is.
What did he say → ... what he said. (注意时态变化，助动词 do/does/did 去掉)
考点2 疑问词 + to do (简化结构)
当主句的主语和宾语从句的主语一致时，宾语从句可以简化为“疑问词 + 不定式 (to do)”结构。
I don't know what I should do. → I don't know what to do.
Can you tell me how I can get there → Can you tell me how to get there
考点3 what 的特殊用法
在宾语从句中，what 既作引导词，又在从句中充当主语或宾语，意为“……的事物”。
I believe what he said. (我相信他说的话。what 作 said 的宾语)
Unit 6 过关斩将
一、单项选择
1. Could you tell me ________
A. where does he live B. where he lives C. where lives he D. he lives where
2. I want to know ________ we will have a meeting.
A. what B. that C. when D. who
3. Do you know ________ the 24 Solar Terms
A. how many B. what is C. how to use D. why is it
4. He didn't tell me ________ he was late for school.
A. why B. what C. which D. who
5. Please show me ________ the machine.
A. how use B. what to use C. how to use D. where use
二、用所给词的适当形式填空
6. I don't know where ________ (buy) the ticket.
7. Can you tell me what ________ (happen) yesterday
8. We represent ________ (we) thoughts in the painting.
9. The boy asked his mother when they ________ (go) to the zoo next week.
三、短文填空（每空一词）
Living with nature is important. In China, the 24 Solar Terms help people understand 10.________ nature works. Farmers follow them to know 11.________ to plant crops and when to harvest. For example, "Grain in Ear" tells farmers that the wheat is ready. Lao Shu, a famous artist, painted the 24 Solar Terms. His paintings show us 12.________ beautiful nature is. In Turpan, people invented the Karez system. Do you know 13.________ it is It is an underground water system. It solves the problem of water shortage. People wondered 14.________ they could get water in the hot desert. The answer is the Karez. It shows 15.________ wise Chinese people are. We should learn to live in harmony with nature. We need to think about 16.________ we can do to protect the environment. I'm not sure 17.________ the weather will be like in the future, but I know that we must take action now. Let's ask our friends 18.________ to join us!2026春外研社版英语八年级下册 Unit 4-6 重点语法归纳
Unit 4 Helping out
语法主题：情态动词 (II) —— 表推测 (Possibility and Deduction)
定义：当我们对某种情况不确定，或者根据已有证据进行推断时，使用表推测的情态动词。本单元主要学习 must, may, might, can, could, can't 在推测时的用法。
考点1 肯定推测
词汇 语气强弱 用法详解与例句
must 最强 (100%) 意为“一定，肯定”。表示有确凿证据或理由做出的肯定判断。
Look at that man! It must be hard for him to carry all the boxes. (看那个人！搬这么多箱子一定很吃力。)
may / might / could 较弱 (20%-50%) 意为“也许，可能”。表示不确定的推测。might/could 比 may 语气更委婉，可能性更小。
That woman looks lost. She might need help. (那个女士看起来迷路了。她可能需要帮助。)
He could be in pain. (他可能很痛。)
考点2 否定推测
表示“不可能”时，使用 can't 或 couldn't，不能用 mustn't。
can't / couldn't: 意为“不可能”。表示有充分理由相信某事不会发生。
It can't be true! (这不可能是真的！)
The man taking a walk can't be Mr. Li. He has gone to Beijing. (那个散步的人不可能是李先生，他去北京了。)
考点3 疑问推测
表示“可能……吗？”或“会是……吗？”，通常使用 can 或 could。
Can this be true (这可能是真的吗？)
Where could he be (他可能会在哪里呢？)
【易错点】mustn't vs can't
1. mustn't 表示“禁止，不允许”，不表示推测。
You mustn't park here. (你不能在这里停车。)
2. can't 表示“不可能”，是 must (肯定) 的反义词。
The news must be true. (肯定是真的) <-> The news can't be true. (不可能是真的)
Unit 4 过关斩将
一、单项选择
1. —Is the man over there Mr. White
—It ________ be him. He has gone to America.
A. must B. can't C. may D. might
2. —Someone is knocking at the door. Who is it
—It ________ be the postman. He usually comes at this time.
A. must B. can't C. need D. shouldn't
3. The notebook on the desk ________ belong to Tom. Look, his name is on it.
A. can't B. mustn't C. must D. need
4. —Where is Betty
—I'm not sure. She ________ be in the library.
A. must B. might C. can't D. need
5. You ________ be serious! He is only a three-year-old boy.
A. can't B. mustn't C. may not D. needn't
二、用所给词的适当形式填空
6. The dictionary ________ (must) be mine. It has my name on it.
7. —Is that red car Mary's
—No, it ________ (can) be hers. Hers is blue.
8. Don't worry. There is a ________ (possible) that he will recover soon.
9. The girl ________ (may) need some help with her heavy bag.
三、短文填空（每空一词）
Helping others makes us happy. Last Sunday, I went to the local hospital to work as a volunteer. At first, I was worried that I 10.________ (can) not do the work well. But the nurses were very kind. They told me that I 11.________ (need) worry. My job was to read books to sick children. When I walked into the room, I saw a little girl crying. She 12.________ (must) be in pain. I went over and gave her a toy bear. "This 13.________ (may) make you feel better," I said. She stopped crying and smiled at me. I realized that a small act of kindness can make a big difference. Some people think volunteering is a waste of time, but it 14.________ (can) be true. It gives us a chance to help people in need. We 15.________ (should) try our best to help others. If everyone offers a helping hand, the world 16.________ (will) be a better place. I'm sure I 17.________ continue to be a volunteer. Helping others is helping 18.________ (my).
【参考答案】
1-5: BACBA (第5题 You can't be serious! "你一定是在开玩笑/你不可能是认真的")
6. must 7. can't 8. possibility 9. may/might
10. could 11. needn't / didn't need to 12. must 13. might/may 14. can't 15. should 16. will 17. will 18. myself
Unit 5 Looking into nature
语法主题：宾语从句 (I) —— that, if, whether 引导
定义：在复合句中，作及物动词或介词的宾语的从句叫宾语从句。本单元重点学习由连词 that, if, whether 引导的宾语从句。
考点1 that 引导的宾语从句
当宾语从句是陈述句时，用 that 引导。that 在口语中常省略，不作成分，无词义。
I think (that) nature is amazing. (我认为大自然很神奇。)
Scientists believe (that) dinosaurs lived on Earth long ago. (科学家相信恐龙很久以前生活在地球上。)
考点2 if / whether 引导的宾语从句
当宾语从句是一般疑问句时，用 if 或 whether 引导，意为“是否”。从句必须用陈述语序。
I wonder if / whether it will rain tomorrow. (我想知道明天是否会下雨。)
Can you tell me if / whether he likes science (你能告诉我他是否喜欢科学吗？)
【易错点】只能用 whether 的情况
1. 与 or not 连用时：whether ... or not.
I don't know whether he will come or not.
2. 在介词之后：
I'm thinking about whether we should go.
3. 后接不定式 (to do) 时：
He hasn't decided whether to go there.
【规划变化】时态呼应原则
1. 主句是一般现在时 → 从句根据实际情况使用任何时态。
2. 主句是一般过去时 → 从句必须用相应的过去时态。
3. 特例：如果从句陈述的是客观真理（如地球绕着太阳转），即使主句是过去时，从句仍用一般现在时。
The teacher said that the earth goes around the sun.
Unit 5 过关斩将
一、单项选择
1. I think ________ amber is a key to unlocking the past.
A. what B. that C. if D. who
2. —Do you know ________ there are any new species in the rainforest
—Yes, scientists found some.
A. that B. if C. what D. where
3. She asked me ________ I could help her with the experiment or not.
A. if B. whether C. that D. when
4. The teacher told us that light ________ faster than sound.
A. travel B. traveled C. travels D. traveling
5. We are not sure ________ they will come to visit the museum.
A. whether B. that C. what D. who
二、用所给词的适当形式填空
6. I believe that we ________ (can) protect the environment well.
7. He asked if I ________ (be) interested in plants.
8. Scientists discovered that the earth ________ (go) around the sun.
9. I'm thinking about ________ (whether) to join the science club.
三、短文填空（每空一词）
Nature is full of secrets. For hundreds of years, people believed 10.________ dinosaurs looked like huge lizards. But recent discoveries changed this idea. Scientists found a piece of amber with a dinosaur tail in it. They were surprised to see 11.________ the tail was covered with feathers! This proves that some dinosaurs 12.________ (have) feathers, just like birds. Amber is like a time capsule. It can tell us 13.________ (what) life was like millions of years ago. Scientists hope to find out 14.________ (if) there are more secrets hidden in amber. Many people wonder 15.________ (whether) we can bring dinosaurs back to life. However, most scientists say 16.________ (that) it is impossible now. Wang Wencai was a great scientist. He spent his life studying plants. He discovered many new species. He showed us that if we observe carefully, we 17.________ (will) find the beauty of nature. Do you want to know 18.________ (if) you can be a scientist like him Just keep curious!
【参考答案】
1-5: BBC CA (第3题or not用whether; 第4题客观真理用一般现在时)
6. can 7. was (主过从必过) 8. goes (客观真理) 9. whether (介词后)
10. that 11. that 12. had 13. what 14. if/whether 15. whether 16. that 17. will 18. if/whether
Unit 6 Living with nature
语法主题：宾语从句 (II) —— 特殊疑问词引导
定义：当宾语从句是特殊疑问句时，由连接代词（who, whom, whose, what, which）或连接副词（when, where, how, why）引导。
考点1 语序（陈述语序）
宾语从句必须使用陈述语序，即“连接词 + 主语 + 谓语”。
I don't know where he is. (我不知道他在哪里。)
Could you tell me when the train will leave (你能告诉我火车什么时候开吗？)
【规划变化】疑问句变宾语从句步骤
1. 保留疑问词（what, where, how 等）。
2. 改语序：将疑问句的倒装语序（谓语在前）改为陈述语序（主语在前）。
Where is he → ... where he is.
What did he say → ... what he said. (注意时态变化，助动词 do/does/did 去掉)
考点2 疑问词 + to do (简化结构)
当主句的主语和宾语从句的主语一致时，宾语从句可以简化为“疑问词 + 不定式 (to do)”结构。
I don't know what I should do. → I don't know what to do.
Can you tell me how I can get there → Can you tell me how to get there
考点3 what 的特殊用法
在宾语从句中，what 既作引导词，又在从句中充当主语或宾语，意为“……的事物”。
I believe what he said. (我相信他说的话。what 作 said 的宾语)
Unit 6 过关斩将
一、单项选择
1. Could you tell me ________
A. where does he live B. where he lives C. where lives he D. he lives where
2. I want to know ________ we will have a meeting.
A. what B. that C. when D. who
3. Do you know ________ the 24 Solar Terms
A. how many B. what is C. how to use D. why is it
4. He didn't tell me ________ he was late for school.
A. why B. what C. which D. who
5. Please show me ________ the machine.
A. how use B. what to use C. how to use D. where use
二、用所给词的适当形式填空
6. I don't know where ________ (buy) the ticket.
7. Can you tell me what ________ (happen) yesterday
8. We represent ________ (we) thoughts in the painting.
9. The boy asked his mother when they ________ (go) to the zoo next week.
三、短文填空（每空一词）
Living with nature is important. In China, the 24 Solar Terms help people understand 10.________ nature works. Farmers follow them to know 11.________ to plant crops and when to harvest. For example, "Grain in Ear" tells farmers that the wheat is ready. Lao Shu, a famous artist, painted the 24 Solar Terms. His paintings show us 12.________ beautiful nature is. In Turpan, people invented the Karez system. Do you know 13.________ it is It is an underground water system. It solves the problem of water shortage. People wondered 14.________ they could get water in the hot desert. The answer is the Karez. It shows 15.________ wise Chinese people are. We should learn to live in harmony with nature. We need to think about 16.________ we can do to protect the environment. I'm not sure 17.________ the weather will be like in the future, but I know that we must take action now. Let's ask our friends 18.________ to join us!
【参考答案】
1-5: BCCAC (第1题陈述语序; 第3题 how to use 简化结构; 第5题 how to use)
6. to buy 7. happened (what作主语语序不变) 8. our 9. would go (主过从必过-过去将来时)
10. how 11. when 12. how 13. what 14. how 15. how 16. what 17. what 18. to

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