The GRE revised general test is administered as a computer adaptive test, but not all sections are computer adaptive. Each of the verbal and quantitative assessment portions of the exam has two parts. The first part is NOT computer adaptive, while the second is.
The first of the two sections for the quantitative and verbal assessment sections has questions that ETS has calculated will be answered correctly by about one-half of the test taker. Based on how well you do on the first section of each assessment, you will be provided with question that are of appropriate difficulty on the second section. For example, if you answer all questions correctly on the first section of the verbal assessment, then the questions that you'll see on the second verbal section will be difficult. Likewise, if you answer incorrectly most of the questions on the first section of the quantitative assessment portion of the exam, then you'll be prompted with easier question on the second section of the quantitative assessment portion of the exam.
Don’t worry about trying to figure out if the current question that you are trying to answer is easy or hard – just be sure to do your best. Even if you do know if the question is hard or easy, does it really matter? You have to answer the question that is presented to youn, so it is irrelevant whether the question is difficult or easy.