How to Stop Contemplating Unaliving your Mandarin Chinese Teacher during Class or Later: 114 pieces of freedom-saving grammar advice with examples, exercises and an answer key
Trust me it will be one of the best choices you'll ever make. Get it, scan borrow it, keep it with you always. It will spare you a lot of dentist fees from all those "Chinese grammar is simple" or "just go with it" moments
This book is an excellent tool for students of Chinese at various levels because it gives real examples of common errors and explains why they are made and provides adequate examples of the proper way of expressing these ideas in Chinese.