Critical Reasoning

Many people have told me that the Powerscore CR bible is the best book out there for CR . I already know the type of questions in CR and I have already finished the Manhattan CR book. Also there is a Powerscore VERBAL book seperately . Which one should I buy ? "Powerscore CR bible" or "Powerscore VERBAL" ? Also I am not an expert in RC's . I make a lot of mistakes on RC one day and the next day , I get many questions wrong . So what should I do to increase my RC score? Also people have told me that
the powerscore CR book will be useful for RC's also ? Is it so ? Will it improve my verbal score? I am getting a verbal score of 33 now and I want to improve my verbal score .

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