Hi alpham,
Scoring at a high level on Reading Comp on the GMAT involves a number of different factors - but understanding everything that the author states is NOT one of them. In simple terms, you have to think more about the 'structure' of what you're reading (WHY is each paragraph and sentence there), recognize the built-in patterns and take the proper notes. Beyond those points, it also helps to know the major question types for RC (and how to go about answering them) and the common wrong answers that regularly show up in RC questions (so you can avoid them). All of this can be learned if you have the proper training materials and if you put in the necessary effort.
1) What 'steps' do you go through when dealing with a typical RC prompt?
2) How long have you studied?
3) What materials have you used?
4) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
5) What is your goal score?
GMAT assassins aren't born, they're made,
Rich