请帮我看一下这篇英语作文是否有错误

Last week,we had a[an] exciting talk .There are something we have learnt.[we learnt much from it.]
Most people thing the student[s] is[are] too young to use the[去掉the 比较好] modern[用cell或者mobile,显然说的是手机嘛] phones.They ofen[may] spend too much time playing games and sending mails[short messages].(发短信是这么写吗?）Also,they may compare their modern[同上] phones with others.
Phones are provided at school if they need[if needed].
I think,it's OK that they want to get fashion[want to be fashionable].(追求时尚）But the mainly[main] task of student is studying[study]