Dear Li Hua
I am glad to receive your e-mail. In your e-mail, I know your problems .You bring the mobile phone to school, but the teacher don’t let you do it. It makes you inconvenient. But this is a school rule. If we break the school rule, we well make the teacher mad at us.
If you really need the mobile phone to get in touch with your parents, you can bring your mobile phone to your teacher .You can ask the teacher to keep it for you. When you need to get in touch with your parents, you can go to the teacher and use your mobile phone.
Yours
Sincerely,
Tom