Unit3 语法专项—— when（时间）& because（原因）从句课件 2025-2026学年沪外教版七年级英语上册

教学课件 沪外教英语七年级上册 Unit3 语法专项—— when（时间）& because（原因）从句 全解精讲+分层练习 1 学习目标 掌握when从句：表“当……时” 掌握because从句：表“因为” 分清主句、从句、语序与逗号 牢记because与so不能同句 什么是从句？ 主句：独立成句，意思完整 从句：不能独立，连词引导 when：时间状语从句（当……时） because：原因状语从句（因为） 例：I’m happy（主句）when I play（从句） when从句 — 含义 when：当……的时候（表时间） 说明主句动作发生的时间背景 时态一致：主现→从现；主过→从过 例：I smile when I’m happy. 例：She cried when she was sad. when从句 — 语序（从句在后） 主句 + when + 从句（无逗号） 结构：S+V … + when + S+V … 例：I listen to music when I’m free. 例：He eats fruit when he’s thirsty. when从句 — 语序（从句在前） When + 从句 + ， + 主句（有逗号） 结构：When + S+V … , S+V … 例：When I’m free, I listen to music. 例：When it rains, we stay at home. when从句 — 时态呼应 一般现在：主现→从现 例：We walk when the sun shines. 一般过去：主过→从过 例：We walked when the sun shone. 口诀：前后时态要一致 because从句 — 含义 because：因为（表原因） 解释主句动作为什么发生 不能单独成句，必须搭配主句 例：I exercise because I want health. 例：She slept early because she was tired. because从句 — 语序 主句 + because + 从句（无逗号） 结构：S+V … + because + S+V … 例：I drink water because I’m thirsty. 例：He studies hard because he likes learning. because 与 so 区别（必考点） because：原因；so：结果 ❌ 同句不能同时用 because + so ✅ I stay in because it rains.（原因） ✅ It rains, so I stay in.（结果） 口诀：有because无so，有so无because when vs because — 快速区分 when：时间 → 当……时候 because：原因 → 因为…… 问“什么时候”→ when 问“为什么”→ because 例：when happy（时间）；because happy（原因） 主从复合句小结 主句：独立完整 when从句：时间；because从句：原因 从句在后：无逗号；从句在前：加逗号 because 不与 so 同句 时态：主现从现；主过从过 选词填空（when / because） 1.I wash hands __________ I eat meals. 2.I eat veggies __________ they’re healthy. 3.__________ you’re tired, take a break. 4.She wears a coat __________ it’s cold. 5.I smile __________ I see my friends. when because When because when 合并句子（用when） 1.I get up early. I go to school. 2.She listens to music. She does homework. 3.We feel happy. We play together. 4.He eats snacks. He watches TV. 5.They run. They are in the park. I get up early when I go to school. She listens to music when she does homework. We feel happy when we play together. He eats snacks when he watches TV. They run when they are in the park. 合并句子（用because） 1.I exercise. I want to be strong. 2.She studies hard. She wants good grades. 3.We sleep early. We feel tired. 4.He eats fruit. It’s sweet and fresh. 5.They help others. It makes them happy. I exercise because I want to be strong. She studies hard because she wants good grades. We sleep early because we feel tired. He eats fruit because it’s sweet and fresh. They help others because it makes them happy. 单项选择 1.I feel relaxed ______ I listen to music. A. when B. because C. so D. but 2.We eat well ______ we want health. A. when B. because C. so D. but 3.______ you study hard, you get good grades. A. When B. Because C. So D. But 4.He didn’t go out ______ he was ill. A. when B. because C. so D. but A B A B 句子改错（每句一处） 1.I happy when I play football. 2.Because I like it, so I do it. 3.When he finish homework, he watch TV. 4.She go to bed early because she tired. I’m happy when I play football. I like it, so I do it. When he finishes homework, he watches TV. She goes to bed early because she’s tired. 易错点总结（一） when=时间；because=原因 从句在前：加逗号；在后：不加 because 与 so 绝对不能同句 when从句：时态必须与主句一致 易错点总结（二） 从句不能单独成句 句首when首字母必须大写 注意主谓一致：he plays / she is 写作多用when/because，句子更丰富 知识梳理（一） when：当……；引导时间从句 because：因为；引导原因从句 语序：主句+从句 / 从句+,+主句 时态：主现从现；主过从过 知识梳理（二） because（原因）↔ so（结果） 主句：独立；从句：依附主句 题型：填空、合并、改写、单选、短文 教学课件 Unit3 语法专项—— when（时间）& because（原因）从句 Thank you for listening! 22 $