Does this make a difference in the meaning in the following sentence if been is included before so long?
Which one of it is correct?
a).It's been so long since we had a meeting that I've forgotten.
b) It's so long since we had a meeting that I've forgotten.
Best Answer
Note that the 's ends up having a completely different meaning in your two sentences:
To my ears, option a) sounds better: you are using the present perfect has been to express the ongoing situation that time has been progressing without any meetings since the last meeting you had (simple past).
Option b) is grammatical, but awkward, since you're using the simple present is to refer to a time period that extends into the past, and then combining with the simple past had. Option a) is definitely the more natural-sounding choice.