课件说明：
The book is intended for more advanced students of English. It is written mainly as a self-study book, but might also be used in class with a teacher. It revises some of the more difficult points of grammar that you will have already studied - such as when to use the, a/an or no article, and when to use the past simple or the present perfect - but will also introduce you to many more features of English grammar appropriate to an advanced level of study.
