mobile phones are useful and popular. but they are also bad for us students. on the one hand, some of us like playing the games, they will forget the time to rest. if they don't get enough rest, they will feel sleepy in class. and even they are having a class, they always think about the games. they are not good for our study. on the other hand, there are a lot of students who like reading e-books on a mobile phone. it's good to read. but reading on a mobile phone for a long time is not good for our eyes.
