汤姆因在学校使用手机被学校处分，他感到很困惑，写信给你求助。

汤姆因在学校使用手机被学校处分，他感到很困惑，写信给你求助。请根据以下结构提示给汤姆回信。开头结尾已给出。

Beginning: Your letter reached me yesterday.It said in your letter that……..     

Paragraph 1: 手机的优点：联系便捷

Paragraph 2: 带手机上学存在的问题：干扰教学，有害学习和健康

Ending: It is right for school to prevent you from using cellphones in school.

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Your letter reached me yesterday. It said in your letter that you were punished for using cellphones, which puzzled you.

There is no doubt that cellphones can bring us much convenience. We can keep in touch with friends and families wherever they are. Besides, the cellphone is a way to fun.

However, there are some problems with using cellphones. The ring of phones can disturb teachers and students in the class. It has been proved that often using cellphones does harm to health. Another problem is that some students can spend too much time and money on cellphones and sending messages, which will result in bad results in study.

As a student, he should concentrate on study. It is right for school to prevent you from using cellphones.