I have been studying for the GMAT and GRE. I have taken a few GMAT CAT practice tests from the GMATprep software I downloaded from the GMAT website. I have managed to test to the level where the CAT software is giving me what it considers difficult questions. I have been stumped on a few and even after going back to review them I either don't see how to arrive at the correct answer or I haven't figured out the fastest way to solve the question. On average I should on spend 2 minutes per question. I will post a few of the problems below. The answer with the blue square is the correct answer. The filled in answer is what I choose. Thanks in advance for those that can help me out.