Unit 6 The power of language-同步【语法】-since&as 引导原因状语从句-2025-2026学年沪外教版八年级下册

该初中英语单元复习讲义围绕since & as引导原因状语从句，通过“核心规则-语义定位-差异辨析-语序标点-易错警示”的框架系统梳理知识，用对比表格明确since/as与because的语义（已知vs未知）、语气（弱vs强），列表呈现as的一词多义（时间vs原因），清晰呈现重难点内在联系。 讲义亮点在于分层练习设计，基础层通过单项选择、选词填空巩固基础用法，提升层借助句子正误判断、中译英强化差异辨析，拓展层结合任务型阅读和书面表达（如“The importance of reading”要求用as/since）培养综合语言运用能力，助力学生提升语言能力与思维品质。易错警示（如“since不能与so连用”）和详细解析支持自主复习，教师可据此实施精准分层教学。

Unit 6 The power of language 同步【语法】-since & as 引导原因状语从句 【同步语法复习】 1、 语法知识点 since /as 引导原因状语从句，用来引出原因 (1) 核心规则 1. 语义定位 · as / since：译为 “由于、既然”，侧重已知、显而易见的原因，听话人本来就知晓这个理由；语气弱于 because。 · because：侧重直接、未知的原因，用来回答 why 提问，语气最强。 区分口诀： 未知原因用 because，已知原因 as/since。 2. as 与 since 用法基本互通，细微语感差异 · As：更侧重伴随、显而易见的理由，常放在句首； · Since：侧重 “既然”，带有双方心知肚明的前提。 绝大多数场景二者可以互换。 3. 语序与标点 ① 从句放句首：As/Since + 从句，主句 ➜ 从句后必须加逗号 例：Since you are tired, you can have a rest. ② 从句放主句后：主句 + as/since + 从句 ➜ 一般不加逗号 例：You can have a rest since you are tired. 4. 易错警示 · 回答 why 的特殊疑问句，不能用 as /since，只能用 because · 不能和 so 连用： 和 though/but 规则一致，有 as/since 就不能出现 so 错误：Since it rained, so we stayed home. 正确：Since it rained, we stayed home. 2、 课本习题 (1) 课本习题C1 Q1 What is the purpose of using since or as in the sentences above? 答案 They are used to introduce the reasons for the main clauses. 句意 句子中使用 since 和 as 的作用是什么？ 解析 as /since 引导原因状语从句，用来为主句陈述事情发生的理由，理由大多是读者已经知晓的信息，语气弱于 because。 Q2 Can we use since to replace as in sentences 1 and 3? 答案 Sentence 1：不建议替换；Sentence 3：可以替换。 解析 句 1：as the King gave the speech 中 as 侧重正当…… 的时候，是时间连词，并非原因连词，因此不能换成 since。 句 3：As your speech depends on who your audience is 此处 as 是原因连词，表示 “由于”，表达原因，可以和 since 互换。 重点区分：as 一词多义：可以作时间连词（当…… 时）、原因连词（由于）；since 只能表原因或时间（自从），无法通用。 (2) 课本习题C2 匹配答案：1-d；2-a；3-c；4-b 1. The vocabulary of the English language keeps increasing since/as it never stops learning from other cultures. 句意：英语词汇量持续增长，因为它不断吸收其他文化的语言元素。 解析：主句说明现象，since/as 引出背后已知原因；从句置于主句末尾，无需逗号。since、as 二者任选其一均可。 2. English changes over time since/as it is greatly influenced by different cultures. 句意：英语随着时代不断演变，因为它深受多元文化的影响。 解析：前半句阐述客观事实，since/as 补充众所周知的诱因；遵循 “主句 + since/as 从句” 结构，不用逗号。 3. English borrows words from other languages since/as these words may be borrowed from other languages. 句意：英语会借用其他语言的词汇，因为部分词汇本身就源自别的语言。 解析：主句提出观点，since/as 提供理由。注意本句描述语言词汇借用现象，as /since 可以互换。 4. Some English words are easy to understand by speakers of other languages since/as these words have rich meanings. 句意：一些英语单词很容易被使用其他语言的人理解，因为这些词汇含义丰富。 解析：主句说明现象，since/as 引出众人易懂的原因；从句位于主句后方，不加逗号。 (3) 课本习题C3 1. B: Yes. I was really moved since/as King George VI made a perfect speech in the end. 句意：是的。我十分感动，因为乔治六世国王最后发表了一场完美的演讲。 解析：原因从句放在主句之后，用 since /as 均可，不用逗号。 2. A: The King trusted Lionel Logue since/as he was a great doctor. 句意：国王信任莱昂内尔・罗格，因为他是一位出色的医生。 解析：主句在前，从句在后，since/as 互换，陈述已知原因。 3. B: Yes. His way of using Shakespeare’s play was effective since/as it helped the King to control his breathing and speaking speed. 句意：没错。他借助莎士比亚戏剧的方法很有效，因为这帮助国王控制呼吸与语速。 解析：从句后置，使用 since/as 引出众所周知的缘由。 4. B: And that famous speech was also meaningful since/as it gave the British people hope in those dark days. 句意：那场著名的演讲意义非凡，因为它在黑暗岁月里给予英国民众希望。解析：主句在前，原因从句后置，选用 since /as。 5. A: Yes. Since/As the King’s speech was encouraging and powerful, it also showed the power of words. 句意：是的。因为国王的演讲振奋人心、铿锵有力，这也展现出语言的力量。解析：原因从句放在句子开头，Since / As 首字母必须大写，从句后搭配逗号，符合本课标点规则。 (4) 课本习题C4 原文划线句改写内容 原句 1：loanwords are very important. They often appear in the most basic English vocabulary. 版本 1（从句后置）：Loanwords are very important since/as they often appear in the most basic English vocabulary. 版本 2（从句前置）：Since/As they often appear in the most basic English vocabulary, loanwords are very important. 句意：外来词十分重要，因为它们大量出现在最基础的英语词汇当中。 解析：“常出现在基础词汇” 是原因，用 since/as 引导已知原因；两种语序都符合本课语法要求。 原句2：We need it to communicate in our daily life. It helps us share our feelings and thoughts with others. 版本 1：We need it to communicate in our daily life since/as it helps us share our feelings and thoughts with others. 版本 2：Since/As it helps us share our feelings and thoughts with others, we need it to communicate in our daily life. 句意：我们日常生活依靠它交流，因为它帮助我们和他人分享感受与想法。 解析：“能够分享想法” 是原因，使用 since/as 引导原因状语从句。 原句 3：Language is also an important life skill. It gives us the ability to tell others what to do in any situation. 版本 1：Language is also an important life skill since/as it gives us the ability to tell others what to do in any situation. 版本 2：Since/As it gives us the ability to tell others what to do in any situation, language is also an important life skill. 句意：语言同样也是一项重要生活技能，因为它赋予我们在任何场景下表达诉求的能力。 解析：后一句为理由，用 since/as 连接；从句放句首时连词首字母大写，从句末尾添加逗号。 【同步语法练习】 ——基础层—— 1、 单项选择 1. —Why won’t you go hiking with us? —____ I have to prepare for the coming test. A. As B. Since C. Because D. When 2. ____ the rain has stopped, we can start our outdoor activity now. A. Because of B. Since C. Although D. So 3. You’d better take a coat ____ it will get cold later in the evening. A. since B. so C. but D. until 4. —We don’t need to hurry. —Right. ____ the meeting will begin at 9:30, we still have plenty of time. A. As B. For C. If D. Though 5. ____ you have finished your homework, you can watch a short video to relax. A. Because B. Since C. What D. Before 6. Don’t worry ____ I will stay here and look after your pet dog. A. so B. as C. but D. though 2、 选词填空（词库可重复使用） as since because so although 1. ____ everyone knows the truth, there is no need for you to hide it. 2. He failed to arrive on time ____ the heavy traffic was terrible. 3. We should speak softly ____ other people are reading books in the library. 4. ____ you are free this weekend, why not visit the city museum with me? 5. She decided to walk home ____ she wanted to enjoy the night view along the street. 6. You can ask Mr. Li for help ____ he has rich experience in this project. ——提升层—— 1、 句子正误判断（正确写 T，错误写 F，并改正） 1. Since it was late, so we decided to go back home. 2. As you know the plan already, I will not introduce it again. 3. —Why did you refuse the invitation? —As I didn’t feel well. 4. Since many trees were cut down, wild animals lost their homes. 5. We stayed inside as the heavy rain. 6. As she practises every day, she plays the piano very well. 2、 中译英（要求使用 as /since） 1. 既然大家都准备好了，我们可以出发了。 2. 由于网上课程十分方便，越来越多学生选择线上学习。 3. 你可以向 Tom 求助，因为他精通英语。 4. 既然你不喜欢这部电影，我们换另一部看吧。 5. 由于城市交通繁忙，骑自行车上学花费我很长时间。 6. 不要打扰他，因为他正在专心写报告。 ——拓展层—— 1、 任务型阅读 Reading Many teenagers enjoy listening to music in their free time. As school life is busy and tiring, music becomes the best way for them to relax. Most students like pop music since its beats are lively and the lyrics are easy to understand. As many parents worry that music will influence students’ study, they stop their children from wearing headphones while doing homework. However, plenty of teenagers hold different ideas. They say soft music helps them keep calm since it can reduce their stress from endless homework and exams. Music also connects people. Since music carries different feelings, it helps teenagers make new friends. They share their favourite singers and songs and communicate with each other. As long as students can control themselves, music will bring more advantages than trouble. Never refuse music simply because you think it is useless. 根据短文内容，简要回答问题 1. Why does music become teenagers’ best way to relax? 2. Why do most students love pop music? 3. What makes many parents stop kids listening to music while studying? 4. How can soft music help students? 5. Why can music help teenagers make friends? 2、 书面表达 题目：The importance of reading 写作要求： 1. 阅读开阔眼界 2. 阅读可以舒缓压力 3. 号召坚持每日阅读 4. 词数 80–100 5. 要求至少两处使用 as/since 参考答案和解析 ——基础层—— 一、 单项选择 1. 答案：C 句意：—— 你为什么不和我们一起徒步？—— 因为我必须为即将到来的考试备考。 解析：回答 why 引导问句，需要直接说明未知原因，只能使用 because；as/since 不用于回答 why。 2. 答案：B 句意：既然雨已经停了，我们现在可以开展户外活动了。 解析：since 放在句首引导已知原因；because of 后接短语，不能接句子；although 表让步；so 不能引导从句。 3. 答案：A 句意：你最好带上外套，因为傍晚晚些时候气温会下降。 解析：since 引导原因状语从句，表示显而易见的理由。 4. 答案：A 句意：—— 我们不用着急。—— 没错，由于会议九点半才开始，我们还有充足时间。 解析：as 置于句首引出双方都知道的理由。 5. 答案：B 句意：既然你已经完成作业，你可以看一小段视频放松一下。 解析：since 带有 “既然” 的含义，前提信息双方已知。 6. 答案：B 句意：不用担心，因为我会留下来照看你的宠物狗。 解析：as 放在主句之后，引导原因从句。 二、 选词填空 1. 答案：Since / As 句意：既然所有人都知道真相，你没有必要隐瞒。 解析：从句位于句首，引出已知事实，使用 As/Since。 2. 答案：because 句意：由于交通拥堵严重，他没能准时到达。 解析：强调直接、新信息原因，选用 because。 3. 答案：as /since 句意：我们应当轻声说话，因为其他人正在图书馆看书。 解析：理由是显而易见的公共规则，as/since 均可。 4. 答案：As / Since 句意：既然你这周末有空，何不与我一起参观城市博物馆？ 解析：引出双方已知的客观情况，用 as/since 引导原因状语从句，位于句首，首字母大写。 5. 答案：because 句意：她决定步行回家，因为她想欣赏沿街夜景。 解析：侧重交代直接、明确的理由，选用语气更强的 because。 6. 答案：as /since 句意：你可以向李先生求助，因为他在这个项目上经验丰富。 解析：理由是显而易见的信息，可用 as 或 since 引导原因状语从句。 ——提升层—— 一、 句子正误判断 1. 答案：F 删去 so 句意：天色已晚，于是我们决定回家。 解析：since 引导原因状语从句，不能与并列连词 so 连用。 2. 答案：T 句意：既然你已经了解这个方案，我就不再介绍了。 解析：as 置于句首引导已知原因，标点、结构全部正确。 3. 答案：F 改正：As → Because 句意：—— 你为什么拒绝邀请？—— 因为我身体不舒服。 解析：回答 why 提问，必须使用 because。 4. 答案：T 句意：由于大量树木被砍伐，野生动物失去家园。 解析：since 后接完整句子，引导双方已知的原因，句式语法正确。 5. 答案：F 改正：as → because of 句意：大雨滂沱，我们待在室内。 解析：as 后面必须接完整句子；the heavy rain 是名词短语，要用 because of。 6. 答案：T 句意：由于她每天练习，她钢琴弹得很好。 解析：as 置于句首引导原因状语从句，后面搭配完整陈述句，用法规范。 二、 中译英（要求使用 as /since） 1. Since / As everyone is ready, we can set off. 解析：原因从句置于句首，since/as 表示 “既然”，从句末尾需要加逗号。 2. As / Since online courses are very convenient, more and more students choose to study online. 解析：as/since 引导原因从句放在句首，引出众所周知的理由，从句后使用逗号。 3. You can ask Tom for help as /since he is good at English. 解析：原因从句放在主句之后，as/since 引导原因，句子中间不需要逗号。 4. Since / As you don’t like this movie, let’s watch another one. 解析：从句位于句首，since/as 意为 “既然”，引出双方清楚的情况，从句后加逗号。 5. As / Since the city traffic is heavy, it takes me a long time to ride to school. 解析：as/since 引导的原因状语从句置于句首，从句末尾添加逗号分隔主句。 6. Don’t disturb him as /since he is putting his heart into writing the report. 解析：as/since 引导原因从句放在主句后面，中间无需使用逗号。 ——拓展层—— 一、 任务型阅读 1. As school life is busy and tiring, music becomes teenagers’ best way to relax. 解析：As 引导原因状语从句置于句首，逗号分隔主句。 2. Most students love pop music since its beats are lively and the lyrics are easy to understand. 解析：since 引导原因从句置于主句之后，不加逗号。 3. As many parents worry that music will influence students’ study, they stop their children listening to music while studying.** 解析：As 放在句首引出家长普遍的顾虑。 4. Soft music helps students keep calm since it can reduce their stress from endless homework and exams.** 解析：since 引导原因从句后置，说明轻音乐的作用原理。 5. Since music carries different feelings, it helps teenagers make new friends. 解析：Since 引导原因从句置于句首，后接逗号。 二、 书面表达 参考范文 The importance of reading Reading is one of the best habits for teenagers. As we can’t travel everywhere, books open a whole new world for us. Since schoolwork brings much pressure, reading helps us relax after long hours of study. When we read, we can forget our trouble for a while. Good books teach us how to behave and think wisely. Don’t spend too much time on short videos. Try to read for half an hour every day. As long as you keep reading, you will slowly find great progress in yourself. 学科网（北京）股份有限公司 $