Hi Akakibedoidze,
From our prior discussions, it seems as though you've been studying for approximately 3 months. With a V21, you're losing significant points in ALL 3 major Verbal categories (RC, SC and CR) - so it might be that your current way of approaching the Verbal section leaves you open to making too many little mistakes. That may or may not have something to do with your vocabulary.
Since it's been about 2 months since we last discussed your studies, I'd like to know a bit more about how you've been studying during that time:
1) What type of study routine have you been following? How many hours do you typically study each week?
2) What study materials have you used over the course of ALL of your studies? What “brands” of CATs/mocks have you used?
3) Have you been studying for the TOEFL at all during this time?
GMAT assassins aren't born, they're made,
Rich