Since 引导的从句不论是延续性或非延续性动词, 都表示的是动作或状态的完成或结束.【已有很多网友发表了看法，点击参与讨论】【对英语不懂，点击提问】【英语论坛】【返回首页】
Since he lived in Nanjing, I have not heard from him. (= since he left Nanjing…)
Since she was in Yangzhou, she has kept in touch with her former friends. ( since she left Yangzhou…)
1). I have never seen him since he was ill.
2). I have never seen him since he fell ill.
It is / ( has been ) + 时间段 + since + 过去式
It is / has been two years since his father died.
= his father has been dead for two years. = his father died two years ago.
It has been 8 years since I graduated from university.
= I graduated from university 8 years ago.
It is 3 years since he smoked. 他三年不吸烟了.(即,从句动词延续性的,译成否定意义;从句动词非延续性的,译成肯定意义.)
It is 3 years since he left school.-----他毕业三年了.