Unit5语法-原因状语从句讲义+练习 2024-2025学年牛津译林版九年级英语上册
译林九上Unit5语法 原因状语从句讲义+练习
原因状语从句定义：指在复合句中表示主句动作发生原因的句子
【考点1】because：“因为”，表示动作发生的直接原因，语气最强
Because he was in a hurry, he left his key home.（因为太匆忙，他把钥匙忘在家里了。）
原因状语从句
①在强调句中强调原因状语从句，只能用because引导，不能用as或since。
例：It was because he was ill that he didn’t go with us.（因为他病了，所以没跟我们一起去。）
②because习惯上不与so连用。
例：Because it was raining, so we stayed at home. ❌
Because it was raining, we stayed at home. ✅
③只有because才能用来回答why的问句
例：--Why were you late for class?（你为什么上课迟到？）
--Because I overslept this morning.（因为我今天早上睡过头了。）
④because vs. because of
because后面接句子；because of后面接名词/代词/名词短语等
例：Many beautiful fish are fast disappearing because of the severe pollution.（由于污染严重，许多美丽的鱼类正在迅速消失。）
⑤关于not...because结构
该结构中的否定词有时否定主句，有时否定从句，一般要根据句子的意思作出正确或合乎逻辑的理解。
例：I didn’t go because I was afraid.（我没有去是因为怕。）
若because之前有just修饰，一般认为not 是否定从句的
例：You shouldn’t get angry just because some people speak ill of you.（你不要因为有人说你坏话而生气。）
【考点2】since：“既然；由于；因为”
表示已知的、 显然的理由(通常被翻译成“既然”= now that )， 较为正式，常放在句首，语气比because弱。
例：Since you are free today, you had better help me with my mathematics.（既然你今天有空，最好帮我做数学题。）
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Since you don't trust him, you should not employ him.（既然你不信任他，就不应该雇用他。）
Now that you are grown up, you should not rely on your parents.（你现在已经长大了，不应该再依赖父母。）
【考点3】as：“因为；既然”
表示附带说明的“双方已知的原因”，含有对比说明的意味，语气比since弱，较为正式，位置较为灵活（常放于主句之前）。
例：As it is raining, you’d better take a taxi.（由于下雨，您最好乘坐出租车。）
As you are tired, you had better rest.（既然你累了，最好休息一下。）
I went to bed early, as I was exhausted.（由于疲惫不堪，我很早就睡了。）
【考点4】for：“因为”
表示原因但并不说明主句行为发生的直接原因，只提供一些辅助性的补充说明，for引导的并列句只能放于主句之后并且必须用逗号将其与主句隔开。
例：He could not have seen me, for I was not there.（他不可能看到我，因为我不在那里。）
He seldom goes out now, for he is very old.（他现在很少出门，因为他已经很老了。）
【补充】复合连词也可以引导原因状语从句，如now that（既然）, seeing that（既然）, in that（因为）, considering that（鉴于）, for the reason that（理由是）...
例：Now that you mention it, I do remember.（既然你提到了，我倒是想起来了。）
Seeing that all the guests have arrived, let’s have dinner.（既然客人都到齐了，那就开饭吧。）
He did quite well in his exams, considering how little he studied.（考虑到他学得很少，他的考试成绩还不错。）
巩固提高练习
1. The Australians are like the English in many ways they have many British relatives.
A. if B. because C. so D. although
2. Jenny, I can't go hiking with you I have to help my mum with housework.
A. so B. but C. because D. unless
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3. I was late for school this morning something was wrong with my bike.
A. but B. because C. if D. and
4. I have to stay at home, it's raining hard.
A. but B. because C. so D. or
5. the weather is very changeable these days, many people have caught a cold.
A. Though B. As C. When D. So that
6. The organizer decided to cancel the concert the tickets didn't sell very well.
A. if B. until C. although D. because
7.— What shall we do now?
— it's raining hard, let's stay at home.
A. So B. Since C. Though D. Otherwise
8. The fridge is environmentally friendly it uses less electricity.
A. because B. until C. before D. though
9. Charlie is Mr. Dancer's eyes, let them in at once.
A. Though B. Before C. Now that D. When
10. I'd like to be a teacher in the future I like children.
A. when B. because C. if D. but
11. All of us like Mrs Brown, she is very nice.
A. or B. because C. so D. but
12. Many people like pandas they are cute.
A. though B. if C. while D. because
13. I can't tell whether she is old or young, I have never seen her.
A. but B. for C. or D. so
14. you know it is harmful, you should stop reading in such a dark place.
A. Until B. Unless C. Although D. Since
15.— Do you know a new shopping mall opened in our town yesterday?
— Yes. Why don't we pay a visit we have time?
A. until B. since C. unless D. though
16.— Who do you think was the greatest inventor?
— Da Vinci was a great inventor he was a pioneer in many areas.
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