since ,for ,as,because做因为是有什么区别

since ,for ,as,because做因为是有什么区别
since ,for ,as,because做因为是有什么区别

since ,for ,as,because做因为是有什么区别
because, as, for, since这几个词都是表示“原因”的连词,语气由强至弱依次为：because→since→as→for;其中because, since, as均为从属连词,引导原因状语从句；而for 是并列连词,引导并列句.
1. because表示直接原因,它所指的原因通常是听话人所不知道的,其语气最强.常用来回答why的提问,一般放于主句之后,也可以单独存在.例如：
(1)I stayed at home because it rained. 因为下雨我呆在家里.
(2)Because Lingling was ill, she didn”t come to school. 玲玲因病,没有上学.
(3)�Why is she absent? 她为什么缺席?
�Because she is sick. 因为她病了.
此外,在强调句型中,只能用because.例如：
(4)It was because I missed the early bus that I was late for school. 我上学迟到是因为我没有赶上早班汽车.
2. since侧重主句,从句表示显然的或已为人所知的理由,常译为“因为”、“既然”,语气比because稍弱,通常置于句首,表示一种含有勉强语气的原因.例如：
(1)Since he asks you, you”ll tell him why. 他既然问你,那就告诉他为什么吧.
(2)Since everyone is here, let”s start. 既然大家都到齐了,我们就出发吧!
(3)Since I understood very little Japanese, I couldn”t follow the conversation. 我日语懂得不多,因而听不懂对话.
3. as是常用词,它表示的“原因”是双方已知的事实或显而易见的原因,或者理由不是很重要,含义与since相同,但语气更弱,没有since正式,常译为“由于,鉴于”.从句说明原因,主句说明结果,主从并重.例如：
(1)We all like her as she is kind. 我们都喜欢她,因为她善良.
(2)As I had a cold, I was absent from school. 因为我感冒了,所以没去上课.
(3)As Xiaowang was not ready, we went without him. 由于小王没有准备好,我们只好不带他去了.
4. for用作连词时,与because相似,但它所表示的原因往往提供上文未交待过的情况.for不表示直接原因,表明附加或推断的理由,因此for被看作等立连词,它所引导的分句只能放在句子后部(或单独成为一个句子),并且前后两个分句间的逻辑关系不一定是因果关系,其间用逗号隔开,且for不可置于句首,for的这一用法常用在书面语中,较正式.例如：

(1)The days are short, for it is now December. 白天短了,因为现在已是十二月份.
(2)It must have rained, for the ground is wet. (从“地面潮湿”作出“下过雨”的推测,但地湿并不一定是下雨所致, for不可以换为because.)
(3)The ground is wet because it has rained. (“下雨”是“地上潮湿”的直接原因.)
前后两个分句间有一定的因果关系时(有时很难区分是直接原因,还是推测性原因),for与because可以互换使用.例如：
(4)I could not go, for / because I was ill. 我没能去,是因为我病了.
(5)He felt no fear, for / because he was a brave boy. 他没有害怕,因为他是个勇敢的男孩

for是用来表示推断的原因或者对主句进行说明的；because引出直接的原因。
because感情最强烈，一般不用于句首，... , becasue...
since和as是从属连词，说明的是已为人们所知和理由。since的语气比because弱，但比as强。since和as引导的从句一般放在句子的开头。since和as的主要区别是：用as引导原因从句语气较弱，所说明原因是附带，而...

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for是用来表示推断的原因或者对主句进行说明的；because引出直接的原因。
because感情最强烈，一般不用于句首，... , becasue...
since和as是从属连词，说明的是已为人们所知和理由。since的语气比because弱，但比as强。since和as引导的从句一般放在句子的开头。since和as的主要区别是：用as引导原因从句语气较弱，所说明原因是附带，而since表示原因暗示着是稍加分析之后才能推断出来原因。
引导原因状语从句的连词
原因状语从句一般由because, since, as, for引导。注意as,because,since和for的区别:
①如果原因是构成句子的最主要部分,一般用because。because引导的从句一般不放在句子的开头。例如:
I missed the train because I got up late.
注:对于以why开头的问句,一般只能用because引导的从句来回答。
②如果原因已为人们所知,或不如句子的其余部分重要,就用as或since、since比as稍微正式一些。as和since引导的从句一般放在句子的开头。
as, since, for 用于句首多，for 不用于句中你百度知道一下 有过一摸一样的问题的 还有你分类弄错了
since 副词 ad. (常用于现在完成时或过去完成时)
1.此后;从那时到现在
She left school three years ago and has worked as a nurse ever since.
她三年前毕业,从那时起便一直当护士。
2.之前,以前
介词 prep.
1.(常用于现在完成时或过去完成时)自...以来,从...至今
I haven't heard from him since last year.
我自去年以来未曾收到过他的信。
连接词 conj.
1.(常用于现在完成时或过去完成时)自...以来,从...至今
It's been ten years since they married.
他们结婚到现在已经十年了。
She has been living a hard life since her husband died.
她自从丈夫死后,一直过着艰苦的生活。
2.既然;因为,由于
He must have taken the book since it isn't here.
他一定是把书拿走了,因为书已不在这里了。
Since it is so hot, let's go swimming.
既然天气这么热,我们去游泳吧。
for
介词 prep.
1.为,为了
They fought for national independence.
他们为民族独立而战。
This letter is for you.
这是你的信。
2.代替;代表
We used boxes for chairs.
我们用箱子当椅子坐。
3.因为,由于
I am sorry for what I said to you.
我后悔不该对你讲那些话。
4.在(指定时间)
The meeting is arranged for 9 o'clock.
会议安排在九点钟。
5.(表示时间、距离等)达,计
You can see for miles from the roof.
你站在屋顶上可以看到数英里之外。
6.对于,关于;在...方面
I am too old for the job.
我年纪太大,做不了这工作。
7.为得到,为赢得
He sent the waiter for a packet of cigarettes.
他让侍者去拿一盒香烟。
8.以...为代价;以...交换
He sold his car for 500 dollars.
他以五百元把车卖了。
9.当作,作为
Do you take me for a millionaire?
你是不是把我当百万富翁?
10.赞成;支持;倾向于
Are you for the government or against it?
你是支持还是反对政府?
11.朝...方向去;往,向
He left for Taipei.
他出发去台北。
12.就...而言
She is sophisticated for her age.
就年龄而言她是世故了一点。
连接词 conj.
1.因为,由于
We must start early, for it will take two hours to drive to the airport.
我们得早点动身,因为开车去机场得花两个小时。
f.o.r.
缩写词 abbr.
1.=free on rail 火车上交货价(价格包括从供应商货场/仓库到车站的运费,买主支付铁路费用)
for-
前缀 pref.
1.表示"禁止";"克制";"无视";"过度";"离";"分"
for.
缩写词 abbr.
1.=foreign(er)
2.=forest(er)(ry)
as
(1) as用作连词
① 作“当……的时候”解，引导时间状语从句，表示从句动作与主句动作同时发生、同时进行。As he looked at her she made a face. 他看她时，她作了个鬼脸。/ He sang as he walked. 他一边走，一边唱。
② 作“由于”、“因为”解，引导原因状语从句，表示比较明显的原因。由as引导的原因从句通常放在主句之前。As he didn't know much English，he got out his dictionary and looked up the word. 由于他不懂得多少英语，他拿出来词典查了这个词。
③ 作“如 (不如)……一样”解，引导方式状语从句或比较状语从句。He does not speak as the other people do. 他不像其他人那样肯说话。He is not so diligent as you. 他不如你勤奋。(so…as…只用于否定句。若为肯定句必须用as…as…)
④引导让步状语从句时，作“虽然”、“尽管” 解，这时，要将表语或状语提到主语之前，使句子部分倒装。如果表语是名词，放在句首时不能加冠词。Young as he is, he knows a lot. 尽管年轻，他懂得很多。Old man as he is, he still works hard. 尽管他是个老人，他仍然工作很努力。
(2) as用作代词
① 作关系代词，引导限制性定语从句，先行词前常有such，the same与之呼应，构成such...as，the same (…) as…。We'll make such computers as are needed in different branches of science. 我们将制造出科学的各部门所需要的那种计算机。/ I'm reading the same books as you. 我读的书与你读的书相同。
②引导非限制性定语从句，as常常作主语、定语、表语等，在这种情况下as指的是前面或后面的整个句子。The two cities are far away from each other, as you can see in the map. 正如你在地图上看见的那样，这两座城市相距甚远。/ As everybody knows, all that glitters is not gold. 大家都知道，闪光的东西不都是金子。
3) as if (as though) 用作连词，作“就像…似的”“仿佛”解
(1) as if (as though)引起的方式状语从句或表语从句中动词一般用虚拟语气, be通常为were或was。如从句动作与主句动作同时发生，从句用一般过去时；若从句动作在主句动作之前发生，从句用过去完成时。Jane shouted in surprise as if she saw the land. 珍妮惊喊着，好像看见了陆地。/ Tom is talking about China as if he had been there. 汤姆正在谈着中国，好像他去过一样。
(2)若主句谓语动词为look，seem，taste，smell等词时，as if引导的表语从句常常使用陈述语气。 It looks as if it is going to rain. 看起来天好像耍下雨。/ This meat tastes as if it has already gone bad. 这肉尝起来好像已变坏了。
(3)当从句中主语和句子主语一致，从句谓语又包含动词be时，这个主语和be可以省略。He glanced about as if (he was) in search of something. 他四处打量着好像在搜寻什么。
(4) as if (as though)可以接一个不定式短语。He waved his hand to me as if to have something to tell me. 他向我挥了挥手好像有事要告诉我。
辨析：as，when与while
as，when，while作为连词，都有“当……的时候”的意思。* as常可与when或while通用，但它较强调主句和从句中的动作或事情同时发生。因此，常作“一面……一面……”解。 * while常表示一段较长的时间或一个过程，强调主句的动词和从句的动词所表示的动作或状态是同时发生的。用while引导的从句中用延续性动词。
As (When／While) I was walking down the street, l noticed a police car in front of Number 37. 我沿着大街往前走的时候，注意到37号门前停着一辆警车。/ When the clock struck twelve, all the lights went out. 钟敲12下时，灯全熄了。/ When I went into the lab, the professor was doing an experiment. 当我走进实验室时，那位教授正在做实验。/ Please keep quiet while others are studying. 别人在学习的时候，请保持安静。/ While I was writing letters last night, he was watching TV. 昨晚我在写信的时候，他在看电视。
误：As he is old, my teacher works hard.
正：Old as he is, my teacher works hard.
尽管我的老师年龄很大了，但是工作很努力。
误：So as to catch the early bus, he got up very early.
正：He got up very early so as to (in order to) catch the early bus. 他起早是为了赶早班车。
拓展：as a matter of fact实际上; as a result (of)结果; as far as就……而言；远至as follows如下as for至于，关于as long as只要; as well as还，也; as to至于，关于; as many as (表可数)和……一样多，达……之多
because
连接词 conj.
1.因为
He is absent because he is ill.
他因病缺席。

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