since做连词和介词的区别.什么情况下SINCE引导的从句瞬间,和静态动词上表动作的结束,

since引导的瞬间动词作连词.表“自从”e.g.1.She moved to London last May and has since got a job on a newspaper.2.It was the first time I'd won since I'd learnt to play chess.since作介词.放于句首或句中....