Please look what Iíve found today:
Hello! It's been a while since I've posted on this board.
Itís a mistake, isnít it? It should be
It's been a while since I posted on this board.
Do you agree with me?
Hi, It`s correct.
started in the past and continued until now -- so present perfect Ok
similarly -- I haven`t seen him since 1979
Indeed, talking abt similarity:
After since there goes a definite moment in the past, a reference point, marked by either a particular date (1979) or an action in the Past Simple.
It's been a while (say, 3 months) since I last posted (On May 11)
Shevchenko has scored 23 goals since he came to the team.
Yes exactly - started in the past. His absence started in the past, when he sent his last message; and he has just returned.
Looking forward to your reply.