This Official Guide from GMAT outshines all others, simply because the
questions are chosen from actual past tests and are very thoroughly
researched. Equally important the answer choices for each question are
also well thought out and both the correct and the incorrect choices
reflect actual test patterns. The explanations for the answers in the
Official Guide are crystal clear and very insightful.
The rules of grammar on which the GMAT Sentence Correction questions
are based are best outlined in this guide. The section on Arguments is