i have know him since i have been here.为什么不成立

i have know him since i have been here.为什么不成立 I have been here since I was born 和I haden't seen him since I HAVE BEEN HERE SINCE TIME 有个小错I HAVE GOT TO KNOW HIM SINCE HE CAME HERE.( )改成( ) I have lived here since then还是I have been here since then对啊? i have known him since he came here I have been here since three yeas ago 在英语现在完成式中 i have lived here since my childhood.i have been i I have lived here since I was born.这个是什么从句．为什么引导词since的前后时态不 I have been sick since yesterday.中have been 是什么是时态为什么要用been. I have been here since last month.（对since last month部分提问） ha I have been here since 1976.请教been(be)的用法.