Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good language book

I've read many books about foreign languages, but this one was by far the most useful. It offers great suggestions on how to succeed in any language by offering tips for studying and memorizing vocabulary. The last part of the book even gives specific tips for eight different languages. It even lists the most common mistakes to watch out for. You should definitely read this if you want to speak another language.