Unit 8单元语法专练- 2025-2026学年沪教版 英语八年级下册

沪教8下第八单元语法专练 原因状语从句 一、原因状语从句的定义 原因状语从句是用来说明主句动作或状态发生原因的从句。它通常由从属连词引导，回答 why 的问题。 二、常用引导词及用法 1. because —— “因为” 语气最强，表示直接的、具体的因果关系。通常用来回答 why 的提问。可以放在主句之前或之后，但放在后面更常见。 He didn't come to school because he was ill. （他没来上学因为他病了。） Because it was raining, we stayed at home. （因为下雨，我们待在家里。） —Why are you late? —Because I missed the bus. （——你为什么迟到？——因为我错过了公交车。） 2. since —— “既然” 语气较弱，表示已知的、显而易见的原因。常翻译为“既然”，通常放在句首，强调已知事实。 Since everyone is here, let's begin the meeting. （既然大家都到了，我们开始开会吧。） Since you are tired, you should have a rest. （既然你累了，就该休息一下。） 3. as —— “由于” 语气最弱，表示双方都知道的原因，或者不太重要的原因。常放在句首，也可放句中。 As it was late, we went home. （由于天晚了，我们回家了。） As you are not ready, we'll wait. （既然你还没准备好，我们就等等。） 4. for —— “因为”（并列连词） for 是并列连词，连接两个并列分句，表示对前面分句的补充说明或推断的理由。不能放在句首，前面通常有逗号。 He must be ill, for he looks pale. （他一定病了，因为他脸色苍白。——推断的理由） I decided to stop and have lunch, for I was feeling hungry. （我决定停下来吃午饭，因为我感到饿了。） 三、引导词用法对比 引导词 语气强度 位置 特点 because 最强 前后均可 直接原因，回答 why since 中等 常放句首 已知原因，相当于“既然” as 较弱 常放句首 众所周知的原因，相当于“由于” for 补充说明 只能放句中，前有逗号 并列连词，表推断或补充 四、注意事项 1. because 和 so 不能同时使用 汉语中常说“因为……所以……”，但英语中 because 和 so 只能用一个。 ✅ Because it was raining, we stayed at home. ✅ It was raining, so we stayed at home. ❌ Because it was raining, so we stayed at home. 2. because 从句可以单独回答问题 —Why didn't you come? —Because I was busy. 3. for 是并列连词，不是从属连词 它连接两个并列分句，不能放在句首引导从句。 ❌ For he was ill, he didn't go to work. ✅ He didn't go to work, for he was ill. 4. because of 后跟名词/名词短语（不是从句） ✅ He was late because of the traffic jam. （因为交通堵塞） ❌ He was late because of the traffic was heavy. 5. 其他表示原因的短语或连词 now that —— “既然”（表示新情况） Now that everyone is here, let's start. （既然大家都到了，我们开始吧。） seeing that / considering that —— “鉴于，考虑到” Seeing that he is young, we should help him. （鉴于他年纪小，我们应该帮他。） 五、专项练习题 Part 1: 选择题 1. ______ you have finished your homework, you can go out to play. A. Because B. Since C. For D. So 2. He didn't attend the meeting ______ he was ill. A. because B. because of C. since D. for 3. It must have rained last night, ______ the ground is wet. A. because B. since C. for D. as 4. ______ it was raining hard, they cancelled the hiking. A. Because B. Since C. Although D. As 5. I was late ______ the traffic was heavy. A. because of B. because C. since D. for 6. ______ you are free tonight, why not come to my party? A. Because B. For C. Since D. As Part 2: 用适当的引导词填空（because, since, as, for, because of） 1. ______ it was getting dark, we decided to go home. 2. He succeeded ______ he worked hard. 3. She didn't buy the dress, ______ she didn't have enough money. 4. ______ you have finished the work, you can leave. 5. He was punished ______ his dishonesty. 6. The day breaks, ______ the birds are singing. （推断） Part 3: 改错题（找出错误并改正） 1. Because he was ill, so he didn't go to school. ________________________________________________ 2. He was late because of he missed the bus. ________________________________________________ 3. For it was raining, we stayed at home. ________________________________________________ 4. Since he is young, but he knows a lot. ________________________________________________ Part 4: 翻译句子 1. 因为下雨，我们取消了野餐。 ________________________________________________ 2. 既然你已经长大了，你应该自己作决定。 ________________________________________________ 3. 他一定很累，因为他很快就睡着了。 ________________________________________________ 4. 由于没有公交车，我们步行回家。 ________________________________________________ 5. 她因为生病没有参加聚会。 ________________________________________________ 6. 考虑到他经验不足，他做得已经很不错了。 ________________________________________________ 六、参考答案 Part 1: 选择题 1. B（既然你完成了作业，可以出去玩了。since表示已知原因） 2. A（他没参加会议因为他病了。直接原因，用because） 3. C（昨晚一定下雨了，因为地面是湿的。for表示推断的理由） 4. A（因为雨下得很大，所以他们取消徒步了。直接原因 用because） 5. B（我迟到了因为交通拥堵。后面是从句，用because；because of后接名词短语） 6. C（既然你今晚有空，为什么不来我的派对？since表示已知条件） Part 2: 填空题 1. As / Since（由于天黑了，我们决定回家） 2. because（他成功了因为他努力工作了） 3. because / for（她没买那条裙子，因为她没足够的钱） 4. Since / Now that（既然你已完成工作，可以离开了） 5. because of（他因为不诚实而受罚） 6. for（天亮了，因为鸟儿在唱歌。for表推断） Part 3: 改错题 1. 去掉 so，或去掉 Because 保留 so。 改为：Because he was ill, he didn't go to school. 或 He was ill, so he didn't go to school. 2. because of 改为 because，或去掉 he missed the bus 改为名词。 改为：He was late because he missed the bus. 或 He was late because of the bus. 3. For 不能放在句首引导从句，应改为 Because / Since / As。 改为：Because it was raining, we stayed at home. 4. Since 和 but 不能连用，去掉 but。 改为：Since he is young, he knows a lot. 或 He is young, but he knows a lot. Part 4: 翻译题 1. We cancelled the picnic because it rained / was raining. 2. Since you have grown up, you should make your own decisions. 3. He must be very tired, for he fell asleep soon. 4. As there was no bus, we walked home. 5. She didn't attend the party because she was ill. / because of her illness. 6. Considering that he is inexperienced, he has done quite well. 学科网（北京）股份有限公司 $