从属连词because,for,since,as辨析，本文主要内容关键词为：连词论文，此文献不代表本站观点，内容供学术参考，文章仅供参考阅读下载。
becausc,for,since,as是常见的引导原因状语从句的从属连词，它们的用法各不相同，这也是各级各类考试中经常出现的重要知识点。为帮助学生更好地使用，现将它们的不同用法归纳如下：
because
1.becausc在这四个词当中表示原因的意思最强，最常用，常表示根本的、直接的、明确的、能够引起事实结果的直接原因。其引导的原因状语从句既可以放于主句前，也可位于其后。
I do it because I like it.我做这件事是因为我喜欢。（表示正是由于“我喜欢”这个原因才使得我做这件事）
I took this road because the policeman told me to.我走这条路是因为警察叫我走的。（强调是警察叫我走这条路的）
Because he is ill,he is absent today.因为他病了，所以他今天缺席。
I am strict with you because I want you to make rapid progress.我对你们要求严格是因为我想让你们迅速进步。
2.because强调的是引起结果的直接原因，因此because可以用于强调句型。
It's because he helped you that I'm prepared to help him.正因为他帮了你的忙，所以我才打算帮助他。
而as,for,since皆不能用于加强语气，所以不能说It is as/for/since...that...。
3.在回答由why引导的问句时，由于问句强调的是未知的、具体的、直接的原因，故回答时只能用because而不能用as,since,for。
——Why did you do it?
——I did it because I was angry.
——你为什么这样干?
——因为我生气了才这样干的。
——Why did you leave us so early?
——Because l had some urgent work to do.
——为什么你那么早就离开我们了呢?
——因为我有点急事要办。
4.because还可用于选择疑问句；as,for,since则不可。
Did they retreat out of panic or because they wanted to save lives?他们后撤是出于慌乱，还是想逃命?
5.because前可用否定词或其他修饰语及并列连词修饰。
I went to this university chiefly because the tuition was cheaper.我之所以上这所大学是因为它的学费更便宜些。
I'm going there tomorrow because I have to,not because I want to.我明天去那里是因为我不得不去，并不是由于我想去。
He looks sleepy not because he is not feeling well,but because he stayed up last night.他看上去昏昏欲睡并不是不舒服，只不过是昨晚熬夜罢了。
6.because所引导的原因状语同时又可表示对主句陈述事实的补充说明或从某一角度对事实的诠释，是为已作出的推断提供的理由，此时用法与for相同，引导的从句只能放在主句后面，不能回答why引导的问句，从句前不可用否定词或其他修饰语及并列连词修饰。because与for可互换使用，但because较多用于口语中。
It must be very late,because/for the streets are quite deserted.天色已晚，因为街上已无行人了。
for
1.for较because正式，一般不用于口语中，其所引导的原因状语从句通常是对主句陈述事实的补充说明或从某一角度对事实的诠释，表示主观推断的、不全面的、非必然的原因，是逻辑上的理由、间接理由，不一定能够引导出事实结果，语气也较弱。所引导的从句只能放在主句后面，并且从句前不能用not...but或其他的连词。
It might have rained last night for the ground is wet.昨晚可能下雨了，因为地面是湿的。（表示说话者从地面湿了这个现象主观推断出昨晚下雨的结论，但事实究竟如何却不得而知）
Long car journeys are even less pleasant,for it isquite impossible even to read.乘汽车作长途旅行使人更加不快，因为车上简直不可能读些东西。（表示从不能读东西的角度说明这种旅行是令人不愉快的）
Frank could hardly conceal his excitement,for he knew that he had made a real discovery.弗兰克几乎不能抑制住自己激动的心情，因为他知道他有了一次真正的发现。
I did it not because I liked it but because I had to do it.我做这件事不是因为我喜欢而是因为我不得不做。（不能用for）
2.for可以单独引导整句，为上文的情况提供补充说明或诠释。
When I saw her swimming in the river,I was frightened.For at that point the currents were dangerous.当我看见她在河里游泳时，我吓坏了。因为那时水流是很危险的。
since
since表示原因，语气比because弱，所引导的原因状语从句的内容常常是谈话双方承认的、已知的客观事实。强调由客观原因引起的结果，即主句所陈述的事实。since前不可用否定词或其他修饰语及并列连词修饰。在正式英语中since引导的从句一般放在主句前，在非正式英语中也可放于主句后。
Since you're not interested,I won't tell you about it.既然你不感兴趣，那我就不告诉你了。（强调“我不告诉你”这个事实）
Since we've no money,we can't buy it.由于我们没有钱，所以买不起这东西。（强调的是“买不起”而不是“没钱”）
I'll do it,since it must be done.既然这事非做不可，那我就来做吧。（强调由“我”来做这件事）
Since you ask,I will tell you.你既然问，我就告诉你。
Since many of the customers work during the day,Billy has to collect the money at night.因为许多顾客白天上班，所以毕利只好晚上去收钱。
as
as在表示原因时同since意思基本相同，一般可以互相代用，但其语气比since弱，并多用于口语，同since一样as前不可用否定词或其他修饰语及并列连词修饰。其所引导的状语从句在正式英语中通常放于主句前，在非正式英语中也可放于主句后。
As his flat is in a large town,he has no garden of his own.由于他住的那套房间在大城市中，所以他没有自己的花园。（强调“没有自己的花园”）
As he was not well,I decided to go without him.因为他身体不好，我决定独自去了。（强调“我独自去了”）
As there are so many people about,the dogs have to be kept in a special enclosure.既然周围有许多人，狗就得关在特制的围栏里。
I am going to bed,as I am very tired.我要去睡了，因为我已非常累了。
填空练习：
1.＿＿＿＿you are tired,you had better rest.
2.Just＿＿＿＿I don't complain,people think I'm satisfied.
3.We must get rid of carelessness,＿＿＿＿it often leads to errors.
4.He stole not＿＿＿＿he wanted the money but＿＿＿＿he liked stealing.
5.＿＿＿＿you ask,I will tell you.
6.＿＿＿＿her father is ill,she is absent today.
7.He must be ill,＿＿＿＿he is absent today.
8.—Why can he leave now?
—＿＿＿＿he is ill,our teacher let him go home.
9.＿＿＿＿you don't want to go,we won't force you to.
10.There must be no one in the house,＿＿＿＿the door is closed.