你是李華。你的朋友Jack因在學校使用手機被學校處分，他感到很困惑，寫信給你求助。請給他回信，內容包括：
1.分析使用手機的利弊；
2.勸說他不要再帶手機回校。
注意：1.寫作詞數應為80詞左右，不多于100詞；
2.開頭結尾已給出。
Dear Jack，
_______
Yours，
Li Hua

【考點】提綱作文．

【答案】Dear Jack，
Hearing that you were punished by the school for using your mobile phone at school，I'm writing to analyse the reasons why students are forbidden to bring their smartphones to school.
Although smartphones have brought great convenience to our study，they have also caused a lot of trouble．What annoys teachers most is that some students spend so much time on smartphones that they ignore their study.What's worse，The ringing phone will interrupt the ongoing course.So there must be a rule to forbid the use of smartphones in class．
So I strongly advise you not to bring your phone back to school.If you would like to call others，the public phone can be used easily.
Yours，
Li Hua