my verbal score is weak, i mean very weak, what are so good verbal books that are geared towards the gmat verbal section.
You're asking for a quick fix - unfortunately, there really isn't one on verbal. Yes, you can memorize a few grammar rules, but to do well on verbal you need to solidify your foundation in English. The best way to do this is simply to read well written and moderately complex materials (Wall Street Journal, Economist, whatever). This will improve your logical thinking skills (for CR), your eye for good grammar (for SC), and obviously your reading speed and skill (for RC).
Any prep guide will give you some grammatical rules to learn and some basic approaches for the other verbal sections, but - more so than does the math section - the verbal section tests skills that subtly tests skills acquired over a long time.
I've had students make reading 30 minutes per day part of their GMAT prep, to set that verbal foundation - I think that's a great idea and will probably improve your score more than a prep guide could.
