Instruct: Classify Amazon reviews into positive or negative sentiment
Query: I have used this book for over two years helping others improve their English

I have been using Improving Spoken English for over 2 years. I teach accent reduction classes as well as individual sessions. I use this book as a foundation. There are two units. The SECOND unit deals with the 15 VOWELS sounds. Most people think of the 'sounds' as what they need to learn to be able to speak English so Americans can understand them better. But, really, even if you use the right 'sounds', but you speak some words too quickly, others will understand you as saying another word. For example, if you say "each" too quickly it will sound basically like "itch". "Green" will sound like "grin", "paper" will sound like "pepper" and "Luke" will sound like "look". The best part of the book is the 'key word system' to learn the vowels. "See It, Say Yes, Fat bird, Bus stop, Two books, No Law, and My Cow boy...