Unit1语法专项课件 时间与原因状语从句 2025-2026学年冀教版英语八年级下册

教学课件 冀教英语八年级下册 Unit1 语法专项—— 时间与原因状语从句 全解精讲+分层练习 1 学习目标 1.掌握时间状语从句（when/while）的定义、结构、时态规则。 2.掌握原因状语从句（because）的用法、时态、禁忌。 3.能精准区分 when 与 while 的使用场景。 4.牢记 because 与 so 不能连用 的必考规则。 5.能完成单选、填空、改写、改错、翻译所有题型。 状语从句总述 复合句 = 主句 + 从句 状语从句在句中作状语，修饰主句的动作。 本单元学习两类： 1.时间状语从句：说明动作在何时发生 2.原因状语从句：说明动作为何发生 从句在前 → 后面加逗号；从句在后 → 不加逗号。 时间状语从句 — 定义 时间状语从句：用来说明主句动作发生的时间。 引导词：when / while 位置：可前可后。 结构： When/While + 从句，主句 主句 + when/while + 从句 核心考点：动词类型 + 时态搭配。 when 用法精讲（1） when：当……时候（使用范围最广） 可接：短暂性动词（瞬间完成）： ring, come, go, start, stop, arrive, see, hear 例：When the bell rang, we stopped talking. 延续性动词（持续一段时间）：live, study, work, read, wait, stay 例：When I lived in the city, I walked to school. when 用法精讲（2）—— 时态规则 1.主从句先后/同时发生 主从句都用：一般过去时 / 一般现在时 例：When he arrived, we began the meeting. 2.长动作被短动作突然打断 主句：过去进行时（长动作）从句：一般过去时（短动作） 例：I was reading when the telephone rang. when 用法精讲（3）—— 时态规则（主将从现） 3.描述将来动作 规则：主句将来时，从句一般现在时（主将从现） 主句：will / be going to + 动词原形 从句：动词用一般现在时（三单要变） 例：When spring comes, we will plant trees. ⚠️ 从句绝对不能用 will！ while 用法精讲（1） while：在……期间（强调“期间”“同时”） 只能接延续性动词/进行时，不能接短暂动词。 错误：While I saw him… 正确：While I was walking… 核心：主从句动作同时持续进行。 常用结构：过去进行时 + while + 过去进行时 while 用法精讲（2）—— 时态规则 1.两个长动作同时进行 主句：was/were doing 从句：was/were doing 例：While I was doing homework, my sister was listening to music. 2.从句表示“背景状态” 例：While the sun was shining, we played outside. ⚠️ while 几乎不用于主将从现。 when vs while 对比表 项目 when while 接动词 短暂/延续均可 只接延续动词 动作关系 可先后、可同时 必须同时持续 结构 进行时 + 一般过去时 进行时 + 进行时 主将从现 可以用 一般不用 瞬间动作 可以用 不能用 原因状语从句 — 定义与结构 原因状语从句：说明主句动作发生的原因。 引导词：because（因为） 结构：Because + 从句，主句 主句 + because + 从句 because 后面必须接完整句子（主语+谓语）。 ⚠️ 不能只接单词/短语。 because 用法精讲（1）—— 时态规则 主从句时态必须保持一致。 主句过去 → 从句过去 例：He was late because he missed the bus. 主句现在 → 从句现在 例：We like spring because it is warm. 作用：清晰表达因果关系。 because 用法精讲（2） ❌ because 和 so 不能在同一句中连用 原因：两个都是连词，功能重复。 错误：Because it was cold, so we stayed at home. 正确：Because it was cold, we stayed at home. 正确：It was cold, so we stayed at home. ⚠️ 只能用一个！ 基础训练1 — 选词填空 1.________ (When/While) I got home, it began to rain. 2.________ (When/While) she was reading, I was drawing. 3.We didn’t go out ___________ (because/so) it snowed. 4.He was sleeping ____________ (when/while) the door opened. 5.They were happy ____________ (because/so) they won. When While because when because 单项选择题 1.We will go for a walk ________ the rain stops. A. when B. while C. because 2.________ I was waiting for the bus, I met my friend. A. When B. While C. because 3.He didn’t come to school ________ he was ill. A. when B. while C. because 4.I was watching TV ________ the power went out. A. when B. while C. because A B C A 5.________ it is fine tomorrow, we will go boating. A. When B. While C. Because 6.They were talking ________ the teacher came in. A. when B. while C. because 7.She didn’t go out ________ she had lots of homework. A. when B. while C. because 8.We will climb hills ________ spring comes. A. when B. while C. because A A C A 用 when / while / because 填空 1.________ the sun was shining, we felt warm. 2.I was doing my homework ________ my father came back. 3.People like spring ___________ it is warm. 4.__________ they were working, it started to rain. 5.We will go to the park ________ we are free. 6.He was late ___________ he got up late. 7.___________ I was sitting there, I saw a bird. 8.She loves music __________ it relaxes her. While when because While when because While because 句型改写（合并句子） 1.It is warm. We can go out.（because） 2.I was watching TV. The bell rang.（when） 3.She was singing. He was dancing.（while） 4.Spring comes. Trees turn green.（when） 5.The weather is nice. We go out.（because） We can go out because it is warm. When I was watching TV, the bell rang. While she was singing, he was dancing. When spring comes, trees turn green. We go out because the weather is nice. 判断句子正误并改正 1.Because I was tired, so I slept early. 2.While I saw him, he was reading. 3.When the wind blow, leaves fall. 4.I was reading when my friend is calling me. 5.While we are having class, the bell rings. 去掉 so While → When blow → blows is calling → called 正确 句子翻译 1.当我在看书时，妈妈在做饭。 2.因为下雨，我们待在家里。 3.当铃声响起时，学生们跑进教室。 4.她喜欢春天，因为有很多花。 5.爸爸在洗车时，我在写作业。 While I was reading, Mom was cooking. Because it rained, we stayed at home. When the bell rang, the students ran into the classroom. She likes spring because there are many flowers. While my father was washing the car, I was doing my homework. 易错点总结 1.when 可接短暂/延续动词；while 只接延续动词。 2.长动作被打断 → 一定用 when。 3.两个动作同时进行 → 用 while。 4.将来时间 → 主将从现，从句不用 will。 5.because 与 so 绝对不能连用。 6.主从句时态必须一致。 7.从句在前 → 必须加逗号。 8.while 不接瞬间动词（see/hear/stop）。 课堂总结（一） when：时间万能词 可短可长，可先后可同时，可主将从现。 while：强调同时持续 只接延续/进行时，常配两个进行时。 because：表原因 后接完整句子，不和 so 连用，时态一致。 课堂总结（二） 掌握 when/while/because = 掌握一类核心句型。 做题三步法： 1.判断：时间 / 原因 2.选引导词 3.核对动词类型与时态 熟练运用可大幅提升阅读与写作能力。 教学课件 Unit1 语法专项—— 时间与原因状语从句 Thank you for listening! 24 $