Some parents agree that smart-phones( 智能手机 ) are bad for students' health and study. They hope their children can keep away from smart-phones. Tang Lin,14, from Changsha, supports parents opinions. He uses a dumb-phone( 非智能手机 )and find that its functions( 功能) are enough for him. Tang once said many students spent much time on games and QQ with their smart-phones. He also said,"If students use smart-phones, they may use them to listen to music, surf the Internet or do some other things. In this way, they may not work hard at their studies. As students, we don't need to use smart-phones. ” But Chen Yu ,16,from Zhuzhou, doesn't think so. She thinks that she can 't live without smart-phones. She said smart-phones are useful. I often use my phone to surf the Internet, chat with my friends and get the latest news. It opens up my eyes. ” Smart-phones have advantages and disadvantages. The key to the problem is how to use smart-phones.In fact, it is a test of students ’ self-control ,Zhangyang ,13, Hengyang ,understands the point well. She said, ” I put my phone out of my sight when I am studying, I also set a time limit about 20 minutes when I use it. I follow these rules so the Smart-phone doesn ’ t affect my life badly. ”