Unit3语法讲解及习题：when和because引导的从句-2025-2026学年沪外教版英语七年级上册

沪外教版英语七上Unit3语法讲解及习题 when和because引导的从句 一、语法详细讲解 结合沪外教版七上Unit3 "Be healthy, be happy" 教材内容，本单元核心语法为 when从句 和 because从句，用于表达时间和原因，是构建复杂句、丰富写作逻辑的关键。 语法点一：when从句（表时间） 1. 核心功能 用于引导时间状语从句，说明主句动作发生的时间背景，可译为“当……时候”。 2. 结构与位置 主句 + when + 从句（从句在后，无需逗号） 例：I feel free like a bird when I'm cycling. 当我骑车时，我感觉像一只自由的小鸟。 When + 从句 + ， + 主句（从句在前，需用逗号隔开） 例：When I'm cycling, I feel free like a bird. 当我骑车时，我感觉像一只自由的小鸟。 3. 时态呼应 当主句为一般现在时，when从句也用一般现在时；主句为一般过去时，从句也用一般过去时。 例：He usually goes to bed early when he has a test the next day. 当第二天有考试时，他通常早睡。 语法点二：because从句（表原因） 1. 核心功能 用于引导原因状语从句，说明主句动作发生的原因或理由，可译为“因为……”。 2. 结构与位置 主句 + because + 从句（从句在后，无需逗号） 例：She tries to get eight hours of sleep every night because she believes getting enough sleep keeps her active during the day. 她每晚尽量睡8小时，因为她相信充足的睡眠能让她白天保持活力。 注意：because从句不能单独成句，必须依附于主句。 3. 与so的区别 because表“原因”，so表“结果”，二者不能在同一句中同时使用。 ✅ I didn't eat much sweet food because it is bad for my teeth. ✅ It was bad for my teeth, so I didn't eat much sweet food. ❌ I didn't eat much sweet food because it is bad for my teeth, so... 语法点三：复合句结构（主从复合句） 主句 (main clause)：能独立成句，表达完整意思。 从句 (dependent clause)：不能独立成句，需依附主句，由when/because引导。 例：I feel free like a bird (主句) when I'm cycling (从句). 二、语法专项习题 第一部分：基础填空 用 when 或 because 填空。 1. I usually drink a glass of milk ___________ I go to bed. 2. I don't eat too much junk food ___________ it is not good for my health. 3. Wendy often does yoga ___________ she feels stressed. 4. We should exercise every day ___________ it can make us strong. 5. ___________ you are sick, you should see a doctor. 6. He likes running in the morning ___________ the air is fresh. 7. I feel happy ___________ I spend time with my friends. 8. She takes an umbrella with her ___________ it is raining. 9. We need to get enough sleep ___________ it helps us study better. 10. ___________ I finish my homework, I can watch TV. 第二部分：句型转换 一、合并句子（用when或because） 11. I drink a lot of water. I play sports. 12. He eats a lot of vegetables. He wants to stay healthy. 13. She feels tired. She works for a long time. 14. We should wash our hands often. We can avoid getting sick. 15. He listens to music. He is doing his homework. 二、改写句子（保持原意） 16. It is raining, so I take an umbrella. (because) 17. When I am happy, I like to sing. (so) 18. I go to bed early because I have a test tomorrow. (so) 19. Because the food is delicious, I eat a lot. (so) 20. I feel relaxed when I listen to music. (so) 第三部分：单项选择 21. I usually go for a walk ___________ the weather is nice. A. when B. because C. so D. but 22. We should eat more fruit ___________ it is full of vitamins. A. when B. because C. so D. but 23. ___________ you are tired, you should take a rest. A. When B. Because C. So D. But 24. He didn't go to school yesterday ___________ he was ill. A. when B. because C. so D. but 25. I like to read books ___________ I have free time. A. when B. because C. so D. but 26. She gets up early ___________ she can catch the first bus. A. when B. because C. so D. but 27. ___________ I finish my work, I will go home. A. When B. Because C. So D. But 28. We need to exercise regularly ___________ it can keep our hearts strong. A. when B. because C. so D. but 29. He feels happy ___________ he helps others. A. when B. because C. so D. but 30. I don't like coffee ___________ it is too bitter. A. when B. because C. so D. but 第四部分：短文填空 用 when 或 because 完成短文。 My Healthy Lifestyle I have a healthy lifestyle. I get up early every morning 31. ___________ I like to run in the park. I run 32. ___________ the air is fresh and it makes me feel energetic. I eat a balanced diet. I eat a lot of vegetables 33. ___________ they are good for my body. I also drink a lot of water 34. ___________ I feel thirsty after exercise. In the evening, I usually read a book 35. ___________ I want to relax before bed. 三、答案及详细解析 第一部分：基础填空 1. when 解析：表示“当我上床睡觉时”，表时间。 2. because 解析：表示“因为垃圾食品对健康不好”，表原因。 3. when 解析：表示“当她感到压力时”，表时间。 4. because 解析：表示“因为锻炼能让我们强壮”，表原因。 5. When 解析：表示“当你生病时”，表时间，句首首字母大写。 6. because 解析：表示“因为空气清新”，表原因。 7. when 解析：表示“当我和朋友在一起时”，表时间。 8. when 解析：表示“当下雨时”，表时间。 9. because 解析：表示“因为充足的睡眠有助于我们更好地学习”，表原因。 10. When 解析：表示“当我完成作业时”，表时间，句首首字母大写。 第二部分：句型转换 一、合并句子 11. I drink a lot of water when I play sports. 12. He eats a lot of vegetables because he wants to stay healthy. 13. She feels tired when she works for a long time. 14. We should wash our hands often because we can avoid getting sick. 15. He listens to music when he is doing his homework. 二、改写句子 16. I take an umbrella because it is raining. 17. I am happy, so I like to sing. 18. I have a test tomorrow, so I go to bed early. 19. The food is delicious, so I eat a lot. 20. I listen to music, so I feel relaxed. 第三部分：单项选择 21. A 解析：表示“当天气好的时候”，用when。 22. B 解析：表示“因为水果富含维生素”，用because。 23. A 解析：表示“当你累的时候”，用when。 24. B 解析：表示“因为他生病了”，用because。 25. A 解析：表示“当我有空的时候”，用when。 26. C 解析：表示“所以他能赶上早班车”，用so。 27. A 解析：表示“当我完成工作时”，用when。 28. B 解析：表示“因为它能让我们的心脏强壮”，用because。 29. A 解析：表示“当他帮助别人时”，用when。 30. B 解析：表示“因为它太苦了”，用because。 第四部分：短文填空 31. because 解析：表示“因为我喜欢在公园跑步”，表原因。 32. because 解析：表示“因为空气清新”，表原因。 33. because 解析：表示“因为它们对我的身体好”，表原因。 34. when 解析：表示“当我运动后感到口渴时”，表时间。 35. because 解析：表示“因为我想在睡前放松”，表原因。 ( 1 ) 学科网（北京）股份有限公司 $