Trả lời: 1. Hi, Lee. What are you doing? c. Oh, hi, Lisa. I'm studying geography.2. I love geography! I can help you. d. Great, thanks! Ask me aquestion then, please.3. OK. What's the longest river in the world? a. Umm, the Nile?4. Yeah! And where's the hottest desert? f. Well, I think it's the Sahara. Is...