Instruct: Classify Amazon reviews into positive or negative sentiment
Query: An absolute MUST!

Two years ago, I went to Mexico with very little speaking ability of the language. I spent two weeks with non-English speaking people, and this was my lifeline to effective communication. Regardless of level of your proficiency, this is essential to learning and provides immediate access to expression of ideas in a form everyone can understand. I still have not exhausted the information in terms of phraseology and idiomatic expressions. I think this will always be my ready reference when I don't know the right word and need it quickly.