I am currently using this book in studying English as a review and I must say that this book is so chock-full of errors that if I had no previous knowledge of English I might be in danger of spending the rest of my life lacking a good working knowledge of grammar. An example of the mistakes in this book would be that it states that "tender" and "lush" are both nouns of quality. They are not. Another example would be that "childhood" is a concrete noun--the book itself states that "concrete nouns refer to persons, places, and objects that you can see, hear, smell, touch, or taste." Childhood concrete? I think not. It amazes me that this book is in its fourth edition and still contains so many mistakes. I'm only on the ninth lesson and have found many more mistakes. My recommendation for anyone looking for a guide on grammar is to look elsewhere.