since

conj

• ①[时间上的一点或一段]自从…之后,从…以来,从…时候起
  • We have both changed since we parted.自从分手之后,我们俩都变了。
  • It is [has been] six years since I left school.自我踏出校门以后已经过了六年了(★可改写为Six years have passed since I left school.)。
  • He had not seen her since he (had) graduated.自从他毕业之后他未曾见过她。

• ②[表理由]因为…;既然…
  • Since it is raining, I'll stay at home.既然在下雨,我就留在家里。
  • She took a lot of clothes with her since she didn't know what the weather was going to be like.因为她不知道天气会怎么样,所以带了很多衣服。