i think the LSAT CR
is a great book, and i definitely recommend it to anyone studying for the GMAT. i think the problem is if you're not a native speaker, the book alone will not be enough to take you to the next level. there's a whole bunch of different tasks you must do before you will see a significant improvement in your verbal score. these tasks cannot happen overnight - they may take a year or more (or less, depending on your level of familiarity with the language).
for native speakers, give yourself at least a month with the LSAT CR
book. go through everything (even the non -relevant stuff) diligently. if you come close to mastering this book, it will help you with most verbal sections, including RC.
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