哪位高手讲解下SINCE的用法

题目

哪位高手讲解下SINCE的用法
I haven’t heard any noise since I slept译为“我醒后还未听到任何声音”.
John is now with his parents in New York,it is already three years since he was a teacher约翰现在和父母一起住在纽约,他不当教师已经三年了.
那这句话呢I have known her ever since she was a freshman
有人翻译为她是新生（或者大一）的时候我就认识她了
但是按照上面的译法好像又不对

答案

since是一个从属连词,它可以引导时间状语从句‘原因状语从句和方式状语从句等,从句既可置于主句之前,亦可置于主句之后．1．从属连词since引导时间状语从句,意谓”自从.以来”．since引导的时间状语从句有两种用法：...