because、as和for这三个词部有“因为”之意,但它们在用法上有所不同。一、because是从属连词,表示直接而明确的原因,它所引导的从句一般放在主句后面,需要强调时,也可以放在主句的前面一。例如: I was late for school this morning because there was an accident on my way to school.今天上学我迟到了,因为我在上学的路上遇到了一起意外事故。It’s best to plant trees in spring becauseit’s warmer.最好春天种树,因为天气暖和。 The three parts because, as and for have the meaning of “because”, but they differ in usage. First, because is a subordinate conjunction, expresses the direct and explicit reason, the clause that it guides is generally placed behind the main sentence, when need to emphasize, also can place in front of the main sentence. For example: I was late for school this morning because there was an accident on my way to school. I was late for school today because I had an accident on my way to school. It’s best to plant trees in the spring because it’s warmer. It’s best to plant trees in spring because the weather is warm.