Sentence completion is a logical part of the exam that tests the students ability to finish sentences with the word that fits the best. The test is similar to other tests the student has seen in other grammar and spelling tests. You are given a partially completed sentence with a list of words. You are asked to finish the sentence with the vocabulary words that best finishes it. Without good knowledge of vocabulary and homonym type words, you will not be able to finish these questions.

The sentences aren't difficult if you are familiar with the meanings of the words in the selected list. The GRE will also test your knowledge of similar sounding words (homonyms), so spelling is important as well. Together, passing this section of the verbal part of the GRE is difficult if you don't have a good foundation on the list of popular GRE vocabulary words.