스마트폰 건강을 해칠 수 있어 (Smartphones Hurt Users) Smartphones are becoming very popular. People use them to work, organize, blog, research and play. However, experts say some smartphone users may have problems. They warn that smartphones ①_____ ______ ________ _______ _______. Common complaints are pain in the arm and wrist. “I started using an iPhone a few months ago. Then ..