because⼀since⼀as⼀ forbecause ⼀as ⼀since⼀ for 有什么区别

　　because\x0d\x0a　　because引导原因状语从句语气最强，表示直接原因,常用来回答由why提出的问题，所引导从句可放在主句前，也可放在主句后。例如：\x0d\x0a　　"Why did you do it?" "Because Carlos told me to".\x0d\x0a　　We can't go to Julia's party because we're going away that weekend.\x0d\x0a　　Because he didn't catch the last bus, he had to walk home.\x0d\x0a　　Why are you late for school ? Because I missed the first bus.\x0d\x0a　　\x0d\x0a　　as\x0d\x0a　　as “由于,鉴于” 主从并重，从句说明原因，主语说明结果。说明比较明显的原因。多用于日常语中，常译为“由于”，从句一般放于主句前。例如：\x0d\x0a　　You can go first as you're the oldest.\x0d\x0a　　As you don't feel well, you had better stay at home.\x0d\x0a　　As he wasn't ready in time, we went without him.\x0d\x0a　　I must stop writing now, as I have rather a lot of work to do.\x0d\x0a　　As it was getting late, I decided to book into a hotel. As it is raining, you'd better take a taxi.\x0d\x0a　　\x0d\x0a　　since\x0d\x0a　　since “因为,既然” 侧重主句，主句表示显然的或已知的理由。强调说话者和听者双方都知道的原因，常译为“既然”，一般用在这样的句子里。例如：\x0d\x0a　　Since we've got a few minutes to wait for the train, let's have a cup of coffee.\x0d\x0a　　Since you are not feeling well, you may stay at home.\x0d\x0a　　Since everybody is here, let's begin the meeting.\x0d\x0a　　Since I am a boy, let me carry the case.\x0d\x0a　　Since/As you are busy, you had better not go with us.\x0d\x0a　　Since we have no money, we can't buy that vase.\x0d\x0a\x0d\x0a　　for\x0d\x0a　　for “因为,由于”表明附加或推断的理由，引导的分句前常有逗号。for分句不放句首.是用来附带解释或说明前一分句的原因和理由。例如：\x0d\x0a　　Day breaks, for the cock crows.\x0d\x0a　　It must have rained last night, for the ground is wet.\x0d\x0a　　I won't go in, for my father is there.\x0d\x0a　　He must be ill, for he is absent.\x0d\x0a　　I went to see him, for I had something to tell him.

because, since,as和for引导的原因状语从句

1 because(因为）：表示直接的原因或理由，着重点在从句，用于回答why，语气最强。

He didn't go to school because he was ill.
Why didn't he go to school? Because he was ill.

2 since(既然）：一般表示对方已知的，无须加以说明的即成事实的理由，全句中心在主句，语气比

because弱。
Since you are ill, I'll go alone.

3 as(由于）：表示十分明显的原因，一般说明因果关系，着重点在主句，语气较弱。

As it is snowing, we shall not go to the park.

4 for(因为，其理由是）：是个并列连词，只能放在另一个并列句后面，表示推理或解释，或用作附加说明，表示新的情况，而不是指理由或原因，语气最弱，一般不放在句首。

The day breaks, for the birds are singing.
* for表示因果关系时，可以同because交替使用，但for前须用逗号，而because则不必。
You couldn't have seen him because he wasn't there.
= You couldn't have seen him, for he wasn't there.

*当原因是显而易见的或已为人们所知，就用as或since，且多放在句首。
Since/ As the weather is so bad, we have to delay our journey.
二 now (that) (既然，现已...所以，当...才）；
Now (that) you've grown up, you should not behave like a child.
Now (that) I am older I see things differently.
Now (that) I have heard the music I understand why you like it.
这两个题我也不会,高考这种题考的不多吧,我们上高三的时候,很少考for的这种用法.如果不明白的话,就把它记住吧.

because[英][bɪˈkɒz][美][bɪˈkɔ:z]
conj.因为

since[英][sɪns][美][sɪns]
prep.自从; 从…以来; 自从…之后;
adv.以后，此后; 后来; （距今几年）以前; （从那时候起几年）以前;
conj.因为; 既然; 自从…以来; 自从…的时候起

as[英][əz][美][æz,əz]
adv.同样地，一样地; 例如;
prep.作为，以…的身份; 如同;
conj.像，像…一样; 由于; 同时，当…时; 尽管;
n.阿斯（古罗马重量单位，约373克）

for[英][fə(r)][美][fɔr,fə]
prep.为，为了; 倾向于; 关于; 当作;
conj.因为，由于

都可以表示原因 都可链接句子。
since 自从
as 表原因、程度、还有表示当……时候
for 表原因，介词