for,since ,because的区别

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)A:Why is she absent?她为什么缺席?B: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。for后可接短语或名词(1)We have studied English for years。我们学英语已有好几年了。(2)They jumped for joy。他们高兴地跳了起来。(3)Jim is going to get material for a new book。吉姆正打算为一部新书准备材料。