This is mentioned in official ETS website (ETS is the org that conducts the GRE):
"In addition to reading widely in a range of fields, you should cultivate the habit of reading closely and critically as you prepare for the GRE Verbal Reasoning measure. Focus on paragraphs that seem particularly dense in meaning and engage actively with the text: how would you sum up the author's larger point? What does a phrase used by the author mean in this specific context? What is not said but implied? Why does the author highlight this particular detail? Where is the argument most vulnerable to criticism? Ultimately, to succeed at GRE reading comprehension, how you read is just as important as what you read."
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