事出有因，没有无因之果，也没有无果之因。生活中我们总在分析与表达事物产生的原因，今天就让我们追随“原因”，去认识发现结果的源泉。OK， let"s go！
21.1原因状语从句的基本用法
原因状语从句表原因，常用的连接词有because（因为），since（既然，由于），as（因为），for（因为），now that（既然），seeing that（既然），considering that（考虑到，因为），in that（在某方面）等。在翻译的时候，大多数原因状语从句可以放在主句之前翻译。
21.2because， since， as 和for 引导的原因状语从句
这四个词都可以引导原因状语从句，其中because 语气最强，一般位于主句之后，用来说明人所不知的原因，用于回答why 提出的问题；since 引导的原因状语从句一般放在主句之前表示已知的、显然的理由（通常被翻译成“既然”），较为正式，语气比because 弱；as 引导原因状语从句时表示附带说明的双方已知的原因，语气比since 弱，较为正式，位置较为灵活（常放于主句之前）；for引导的是并列从句，是对前面的从句加以解释，说明推断的理由，只能后置，并且必须用逗号将其与主句隔开。
1.because 引导的原因状语从句
例如：
He didn"t go to Mary"s birthday party because he was not invited.
他没去参加玛丽的生日晚会，因为他没有被邀请。
I went to bed early yesterday evening because I was very sleepy.
昨天晚上我睡得很早，因为我太困了。
- Why do you look so sad？
你为什么这么难过？
- Because I failed my math exam.
因为我数学考试不及格。
2.since 引导的原因状语从句
例如：
Since this method doesn"t work， let"s try another one.
既然这个方法行不通，我们就试试另一个吧。
The football match was delayed， since it was raining heavily.
因为雨下得很大，足球赛延期了。
Since he has no license， he is not allowed to drive.
因为他没有驾照，所以不可以开车。
Since I"m not interested in classical music， I"ve decided not to go to the concert.
因为我对古典音乐不感兴趣，所以我决定不去参加音乐会了。
3.as 引导的原因状语从句
例如：
As I didn"t know how to do it， I asked the teacher.
由于我不知道怎样做，就问了老师。
As she had nothing in particular to do， she turned on the TV and saw a movie.
由于没什么具体的事儿做，她打开电视看电影。
4.for 引导的原因状语从句
例如：
Helen could not have seen me， for I was not there.
海伦不可能见过我，因为我不在那里。
It must have rained last night， for the ground was quite wet this morning.
昨夜一定下雨了，因为今天早上地面很湿。
It must be morning now， for the birds are singing.
天一定亮了，鸟儿在唱歌。
Dialogue & Analysis（此处有视频学习资料）
A： Hey， my sweetheart， time to get up for school.
B： Daddy， I want to stay at home， for I didn"t feel well today.（for 引导原因状语从句，只可放在主句之后，for之前需加逗号。）
A： You look very sick.You"d better take some medicine.
B： I want neither medicine nor water.（neither … nor …， either … or …， not only … but also …等并列连词所连接的部分应是相同词性或起相同作用的结构，不可说“I neither want medicine nor water.”。）
A： But you"re sick， my dear.
B： I don"t want water or medicine.（在否定句中，并列连词一般不用and，而用or。）
A： OK， either you or I am to obey.（在含有either … or … 的句子中，谓语动词的数由较近的主语决定。）I obey you this time， but with one condition.
B： What is it？
A： Although you are sick， you should study.（though 或although 本身就有“虽然……但是……”的意思，不可再和but 连用。）
B： I will study here in bed.No problem.
A： Because I have to go out， I can"t stay with you now.（because 本身就有“因为……所以……”的意思，不可再和so 连用。）
B： I won"t get out of bed until you come back.（not until 表示“到……时候才”。在此句中，get out of bed 的动作要等到爸爸回来时才发生。）
A： I"ll come back soon.Be a good boy！ Bye！
B： Bye-bye， daddy....You"re back so soon.Anything wrong？
A： I just forget my something.Oh， you look terrible.Are you OK？
B： I， I just don"t feel quite well.That"s all.
21.3now that， seeing that， in that， considering that 等引导的原因状语从句now that， seeing that， in that， considering that 这几个词与since 引导的原因状语从句意思相近，都表示“因为，既然”。例如：
Now that you have graduated from college， you should be financially independent.
既然你已经大学毕业了，就应该在经济上独立了。
Now that he is free， he can help you solve the problem.
既然他现在有空了，就能够帮你解决那个问题了。
Seeing that it"s very cold outside， let"s stay inside this afternoon.
因为外面很冷，今天下午咱们待在室内吧。
Seeing that he"s terribly ill， he is unlikely to attend the meeting.
他病得很重，不可能来开会了。
He is quite different from other students in that he speaks three foreign languages.
他跟其他学生不同，因为他说三种外语。
This is not a good book for children in that its content is unhealthy.
这本书不适合儿童阅读，因为它的内容不健康。
Considering that he is only ten， he skates pretty well.
他仅仅十岁，从这一点看，他滑冰滑得真不错。
Considering that there"s no enough money for a new bike， he decided to buy a second-hand one.
因为没有足够的钱买新自行车，所以他决定买辆二手的。
21.4使用原因状语从句时的注意事项（1）英语中的“因为”不跟so 连用。例如：
Because his bike was broken halfway， so he was late.(Chinglish)
Because his bike was broken halfway， he was late.(English)
因为自行车半道儿坏了，所以他迟到了。
（2）回答疑问句why 时，或用在强调结构中，或有just， all， only， part， but 等词修饰时，都只能用because。例如：
It was because she was too lazy that she failed.
她因为太懒惰而失败。
（3）because 引导的原因状语从句中如果主句为否定句，主句和后面的从句没有逗号隔开，这时not 修饰的是后面的从句。例如：
You should not despise them because they are poor.
你不能因为他们穷就看不起他们。
（4）表示双方都知道的原因时用as， since， now that 引导，且一般放在句首。例如：
Now that the semester is over， I"m going to do what I like in my spare time.
这学期结束了，我要用课余时间做我喜欢做的事情了。
（5）由for 引导的表示原因的分句，位于主句后面，对主句加以说明。例如：
Mary shook her head， for she had a different idea.
玛丽摇了摇头，因为她有不同的观点。
I.选择题。
1.I don"t know what decision was taken at the conference the representative hasn"ttold me yet.
A.as
B.because
C.for
D.provided
2.Criticism and self-criticism is necessary it helps us to correct our mistakes.
A.but that
B.in that
C.except that
D.now that
3.The ship changed its course there was a storm.
A.on account of
B.due to
C.thanks to
D.because
4.He married he loved her but because he was indebted to her.
A.because not
B.not because
C.because
D.though
5.It must have rained last night， the ground is still wet.
A.as
B.for
C.because
D.since
6.Many experts are strongly opposed to opening up a coal mine there it will cause a great deal of damage to the environment.
A.since
B.while
C.in that case
D.as long as
7.you have finished reading the book， you should start doing some exercises.
A.For now
B.Since that
C.Now that
D.Since now
8.He found it increasingly difficult to read， his eyesight was beginning to fail.
A.and
B.for
C.but
D.or
9.he"s got a chance， he might as well make full use of it.
A.Now that
B.After
C.Although
D.As soon as
10.nobody was very enthusiastic about it， they decided to cancel the match.
A.Considering that
B.So
C.Provided
D.For
II.根据所提供的信息，用now that造句。
1.We have to wear warm clothes.It"s winter now.
2.Mary used to live in the dorm， but a month ago she bought an apartment.Now she can cook her own food.
3.I"ve learned Japanese quite well now.I can get a job as a bilingual teacher.
4.You can go shopping with me.It is weekend now.
5.He is sixteen.He can get a driver"s license.
III.用适当的连词填空（每空一词）。
1.Jenny was the eldest， she looked after the others.
2.you know it， I won"t repeat it.
3.Ann didn"t hear the knock at the door she was listening to the radio.
4.- Why didn"t Tom come？
- his father wouldn"t let him.
5.everybody is here， let"s begin the meeting.
Fun Time
状语从句小笑话
我们在学习英语状语从句的时候，如果混淆了生活中的一些逻辑关系，会经常闹出笑话来。请看：
时间状语从句
正： The sky was very dark before the sun came out.
误： The sun came out before the sky was very dark.（原来天空变黑暗了是因为太阳出来了！？）
条件状语从句
正： If you don"t work hard， you won"t pass the exam.
误： If you don"t pass the exam， you won"t work hard.（如果你通不过考试，你就不会努力学习！？）
目的状语从句
正： I work hard so that I can go to a university.
误： I go to a university so that I can work hard.（原来上大学是为了更努力地学习啊！？）
让步状语从句
正： Although it was raining hard， we still had the sports meeting.
误： Although we still had the sports meeting， it was raining hard.（原来老天爷尽管看到我们在开运动会还是要下雨啊！？）原因状语从句
正： We didn"t go out because it was raining heavily.
误： It was raining heavily because we didn"t go out.（老天爷见我们没有出门，就赶紧下雨了，挺人性化的！）
语言就是这么精彩，同样的词汇，不管用什么语言，都可以组合成不同的意思，所以，在使用状语从句的时候，不可忽视自己理解能力和逻辑思维能力的提高。