With the development of science and technology ,more and more students have their own mobile phones .Of course ,it is convient for them to keep in touch with others but on the other hand some students use them to cheat in the exams .They use them to send answers ,which will certainly affect their study .Because they have formed the habit of cheating and become lazier and lazier .At the same time they have cheated their parents and waste their limited time ,which should have been spent on their study .So I think mobile phones are not very good for students.At least we should make proper use of them .Only in that way can it be a useful tool.