Unit5语法(原因状语从句)讲解与练习-2026-2027学年沪教四五学制版英语八年级上册

该初中英语导学案围绕Unit5 Teamwork主题，聚焦原因状语从句（because/since/as/now that）的语法知识，通过定义阐释、引导词分层详解、四者对比表及核心易错清单搭建学习支架，帮助学生从简单句过渡到复合句的理解与运用。 资料以Teamwork为语境，通过分层对比引导词语气、含义及位置差异，结合易错清单强化规范使用，配套多样化练习（选词、单选、句型改写、汉译英），有效提升学生语言理解与表达能力，培养对比分析的思维品质，促进自主学习能力的发展。

Unit5 Teamwork语法讲解与练习 原因状语从句（because /since/as /now that） 1. 定义 在复合句中，由连词引导、用来交代主句动作发生原因的从句，叫作原因状语从句。 常用引导词：because, since, as, now that 2. 四个连词分层详解 （1）because ✅ 语气最强，强调事情最直接、根本的客观原因。 ✅ 唯一可以用来回答 Why…? 问句的连词。 ✅ 位置灵活：可置于主句前，也可置于主句之后（日常最常用放主句后面） 句式： *主句+ because +原因从句 *Because +原因从句,主句. We need teamwork because one person cannot finish all the work. Because communication is important, we should talk with teammates often. 问答示范： —Why do you value teamwork? —Because many jobs need joint efforts. ⚠️ 【必考错误】because 和 so 绝对不能连用！ ❌ Because we worked hard, so we won. ✅ Because we worked hard, we won. （2）since ✅ 语气弱于 because，翻译为既然。 ✅ 理由是说话双方都已经知道、显而易见的事实。 ✅ 大多放在句首。 句式：Since +从句,主句. Since everyone arrives on time, let’s begin our team project. 既然所有人都到了，我们开始小组任务。 💡拓展提醒：since一词多义 ① 既然（原因状语从句） ② 自从（时间状语从句） （3）as ✅ 语气比 since 更弱，翻译为由于。 ✅ 多用于书面语，只是附带提及原因，不突出强调理由。 ✅ 通常放在句首。 句式：As +从句,主句. As we are a team, we should help each other. 由于我们是一个团队，我们应当互相帮助。 （4）now that ✅ 翻译：既然；由于 ✅ 重点：强调刚刚出现、新知晓的情况，带有 “如今既然已经……” 的含义。 ✅ 一般置于句首。 句式：Now that +从句,主句. Now that we know our mistakes, we can make a new plan. 既然我们已经清楚失误所在，我们可以制定新方案。 3. 四者完整对比表 引导词 语气强弱 核心含义 使用要点 典型位置 能否回答Why? because 最强 因为 直接、根本原因 句首 / 句末 ✅ 可以 since 中等 既然 双方已知的事实 大多句首 ❌ 不可以 as 较弱 由于 附带说明理由，偏书面 大多句首 ❌ 不可以 now that 最弱 既然 强调新出现的事实 大多句首 ❌ 不可以 4. 通用句式结构总结 主句+ because +从句 Because / Since / As / Now that +从句,主句 5. 核心易错清单 because不能与so 连用； 回答Why 提问,只能使用 because； since 存在一词多义，区分 “自从” 和 “既然”； now that 侧重 “新情况”，不要和 since 随意无条件互换； 从句遵循时态一致逻辑：过去发生的事情多用过去时态，常态事实用一般现在时。 【配套练习】 Ⅰ. 选词填空（because /since/as /now that） 1.________ we form a team, we need to respect different ideas. 2.We keep communicating ________ misunderstandings appear easily without talks. 3.—Why do you learn to cooperate with others? —________ nobody can finish hard work alone. 4.________ you have joined our group, you should take your share of work. 5.The team lost the game ________ members didn’t trust one another. 6.________ the task has changed, we have to discuss a new plan. 7.________ time is limited, we must finish the task as soon as possible. 8.Don’t blame him ________ he has tried his best. 9.________ everybody knows the rules, we do not need to explain again. 10.I believe my teammates ________ they are ready to give me support. 11.________ we have divided all the work, let’s start right away. 12.We need good teamwork ________ single power is limited. 13.________ our team leader comes back, we can hold the meeting. 14.She takes part in the activity ________ she wants to improve teamwork skills. 15.________ you understand teamwork’s importance, you will cooperate better. Ⅱ. 单项选择 1.We help each other ______ teamwork makes us stronger. . because B. so C. but D. though 2.—Why won’t you finish the work alone? —____ one person cannot do everything well. A. Since B. As C. Because D. Now that 3.______ all members are ready, let’s start the team competition. A. Because B. Since C. So D. But 4.He practises cooperating ______ he wants to make progress in group work. A. so B. because C. though D. if 5.______ you know your weak points, you can ask teammates for help. A. Now that B. But C. Although D. Unless 6.Because we helped each other, ______ we won the competition. A. so B. / C. and D. then 7.______ the task is difficult, we need to work together closely. A. As B. So C. But D. Though 8.I trust my teammates ______ they are honest and hard-working. A. since B. because C. as D. now that 9.______ it is getting late, we should speed up our project. A. Because B. As C. But D. If 10.—Why is teamwork important? —______ great success needs joint efforts. A. As B. Since C. Because D. Now that 11.______ we have enough members, we can separate different jobs. A. Now that B. But C. Though D. Before 12.Don’t give up ______ your teammates are still fighting for the goal. A. so B. because C. although D. when 13.______ we have made mistakes, we should find ways to correct them. A. Because B. So C. And D. If 14.Since we are partners, ______ we should share difficulties together. A. so B. / C. but D. then 15.______ you have experience in this task, please offer us some advice. A. Now that B. Though C. Until D. While Ⅲ. 句型改写 1.We work closely. We want to finish the group task.（用 because 合并句子） _______________________________________________________________ 2.Now that you know the problem, let’s solve it together.（用 since 改写） _______________________________________________________________ 3.Because we lacked communication, so we had lots of trouble.（修改病句） _______________________________________________________________ 4.Everyone should take part. Teamwork needs everyone’s effort.（用 because 合并） _______________________________________________________________ 5.As time is short, we cannot waste minutes.（用 since 改写） _______________________________________________________________ 6.Why do you like working in groups?（用 because 写出完整答句） _______________________________________________________________ 7.We trust our teammates. They always keep their promises.（用 because 合并） _______________________________________________________________ 8.Since the plan is ready, we can start working.（用 now that 改写） _______________________________________________________________ 9.Because he was careless, so he made the team lose points.（修改病句） _______________________________________________________________ 10.You have joined our team. You need to follow team rules.（用 now that 合并） _______________________________________________________________ Ⅳ. 汉译英 1.我们需要合作，因为一个人很难完成这项任务。 _______________________________________________________________ 2.既然大家都到齐了，我们可以讨论小组方案。 _______________________________________________________________ 3.由于我们是一个团队，我们应当互相体谅。 _______________________________________________________________ 4.既然你已经知道团队目标，就要尽力付出。 _______________________________________________________________ 5.他获得大家尊重，因为他愿意帮助队友。 _______________________________________________________________ 6.因为缺少交流，小组出现了一些误会。 _______________________________________________________________ 7.既然困难已经出现，我们一起想办法克服。 _______________________________________________________________ 8.由于时间有限，我们必须分工合作。 _______________________________________________________________ 9.— 你为什么重视团队合作？ — 因为团结力量大。 _______________________________________________________________ 10.既然我们已经吸取教训，下次我们会做得更好。 _______________________________________________________________ Keys Ⅰ. 选词填空 1.As 2.because 3.Because 4.Now that 5.because 6.Now that 7.As 8.because 9.Since 10.because 11.Now that 12.because 13.Since / Now that 14.because 15.Now that Ⅱ. 单项选择 1.A 2.C 3.B 4.B 5.A 6.B 7.A 8.B 9.B 10.C 11.A 12.B 13.A 14.B 15.A Ⅲ. 句型改写 1.We work closely because we want to finish the group task. 2.Since you know the problem, let’s solve it together. 3.Because we lacked communication, we had lots of trouble. 4.Everyone should take part because teamwork needs everyone’s effort. 5.Since time is short, we cannot waste minutes. 6.I like working in groups because we can learn from each other. 7.We trust our teammates because they always keep their promises. 8.Now that the plan is ready, we can start working. 9.Because he was careless, he made the team lose points. 10.Now that you have joined our team, you need to follow team rules. Ⅳ. 汉译英 1.We need to cooperate because it is hard for one person to finish the task. 2.Since everyone is here, we can discuss the group plan. 3.As we are a team, we should understand each other. 4.Now that you know the team goal, you should try your best. 5.He gets respect from others because he is ready to help his teammates. 6.Because the group lacked communication, some misunderstandings appeared. 7.Now that difficulties have appeared, let’s think of ways to overcome them. 8.As time is limited, we must divide the work and cooperate. 9.—Why do you value teamwork? —Because unity makes us strong. 10.Now that we have learned the lesson, we will do better next time. 2 / 2 学科网（北京）股份有限公司 $