Question

because，since，as和for的区别

Answer 1

　　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.

Answer 2

since, as because,for都可表示原因，它们的区别是：

1. Becasue：当原因作为句子或陈述最重要的一部分时，我们使用because.
Because通常出现在句首部分。
Because is used when the reason is the most important part of the sentence or utterance. The because clause usually comes at the end:
e.g. I went to Spain last summer because I wanted the guarantee of sunshine on every day of my holiday.

2. As和since：当原因是众所周知时，我们使用as和since，因此，这样的原因一般不那么重要。
as或since从句一般置于句首。
As and since are used when the reason is already well known and is therefore usually less important. The as or since clause is usually placed at the beginning of the sentence:
e.g. As the performance had already started, we went up to the balcony and occupied some empty seats there.
e.g. Since John had already eaten, I made do with a sandwich.

3. For：For意味着原因是事后给出的。
For从来都不会置于句首，带有书面英语而非口语的色彩。
For suggests that the reason is given as an afterthought. It is never placed at the beginning of the sentence and is more characteristic of written, rather than spoken English:
e.g. I decided to stop the work I was doing - for it was very late and I wanted to go to bed.