Hi SISDIT,
There's a significant difference between performing well on a set of RC prompts in a book and performing well on RC while taking a full, adaptive CAT (in which you'll have to 'jump' between RC, SC and CR). Since you haven't provided any information on your CAT Scores, before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What study materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)? Please list each Exam.
Goals:
4) What is your goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich