Hi-- I'd like to support Rose_Queen's recommendation: use your Elsevier study guide, but also consult a few other grammar sources. Other authors will present the material in different ways, and another book or site might click for you. No Fear Grammar is one book you might try, but your library will likely have a selection. Working through a few new sources could give you the confidence you need. The HESI grammar section isn't dreadful, but you'll do best when you feel prepared. It sounds like you are working hard to succeed, and I wish you the best. Good luck!