because，since，as和for的区别

because，since，as和for的区别

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，使用because，Because通常出现在句首部分。
　　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，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. 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。
　　e.g. I decided to stop the work I was doing - for it was very late and I wanted to go to bed.