This book is different from that book in that this one is about chemistry and that one about history.这本书不同于那本，因为这本是有关化学的，而那本是有关历史的。In this class, you will learn the basic principles of chemistry.在这节课上，你们将会学到化学的基本原理。I have only a rudimentary grasp of chemistry.我只掌握了化学的初步知识。