Dear xiaoling,
I have got your letter, in your letter, which you told me that you were thinking of buying an iPhone4. I don't think it is a very good idea. First of all, it will affect your study if you spend a lot of your time playing games or send short messages with it. Secondly, cellphones are not allowed to be used in school in order not to disturb others.Thirdly people often receive many false messages, which you may find yourself being cheated. Finally this kind of cellphones is very expensive that the expenses will certainly increase your parents' burden. So I suggest that you should think carefully before you decide to buy it and please consider this is just my concerned advice to you as a friend.
Best friend of yours