Dear Li Lei,I'm glad that you write a letter to me.In your letter,I knew you wanted to buy a cellphone.In my view,I don't think you have better to buy a cellphone.Let me tell you some bad effects to use a cellphone.To begin with,you know the cellphon

Dear Li Lei,I'm glad that you write a letter to me.In your letter,I knew you wanted to buy a cellphone.In my view,I don't think you have better to buy a cellphone.Let me tell you some bad effects to use a cellphone.To begin with,you know the cellphon
Dear Li Lei,
I'm glad that you write a letter to me.In your letter,I knew you wanted to buy a cellphone.In my view,I don't think you have better to buy a cellphone.
Let me tell you some bad effects to use a cellphone.
To begin with,you know the cellphones aren't allowed to use at the school.Because it will disturb other people.Next,it takes too much time to send the short message.Maybe it is bad for our studys,What's more,you often receive some bad messages.Last but not least,the charge of the cellhones will be increase parents' encomy afford.
Please think about it.
Thanks,

Dear Li Lei,I'm glad that you write a letter to me.In your letter,I knew you wanted to buy a cellphone.In my view,I don't think you have better to buy a cellphone.Let me tell you some bad effects to use a cellphone.To begin with,you know the cellphon
write- wrote
have- had
the cellphones- cellphones
to use- to be used
at the school- at school
the short - short
message- messages.
Maybe- Therefore
studys- studies
will be increase--will increase

标有数字部分为修改部分

• I'm glad that you 1.(write改为wrote) a letter to me.In your letter,I knew you wanted to buy a cellphone.In my  view,I don't think you 2.（have改为had) better to buy a cellphone.
     Let me tell you some bad effects to use a cellphone.
      3.（To begin with改为at first),you know the cellphones aren't allowed to use at the school.Because it will disturb other people.Next,it takes too much time to send the short message.Maybe it is bad for our studys,What's more,you often receive some bad messages.Last but not least,the charge of the cellhones will 4(be increase改为increase) parents' encomy afford.
     Please think about it.

  修改只是针对某些词的用法，没有针对整篇文章的用词及修饰是否妥当，

  可以自己斟酌润色一下。