<p>Thoe most difficult of those 3 sections to improve is the sentence completion, which involves quite simply knowing words. I recommend both the Direct Hits volumes for that.</p>
<p>You don’t reall need books for grammar. If you ask anyone they will tell you grammar is the easiest section to improve in. Just reading silverturtle’s guide boosted my writin score by about a 100 points. A few practice tests later, I only get 1 or 2 wrong in writing now.</p>