Dear wang bing,
Hell!I have received your letter and I'm quite sorry to know your problem.You said that some of your classmates around you are usually absent from school and smoke.You dislike them but you can't get rid of them,which is upetting you a lot.Come on,Wang Ping,it's nothing.Almost everybody at your age has the such a problem.And so it was with me .What's important is that we should know which is right or not and then make a correct choice.Let's face it bravely.We shouldn't do as they do.We should have good habit.Besides,we should help those classmates who are in trouble.We should try to persuade them to get rid of the bad habit and get on well with them.
I believe you can do it and will be happy again.
best wishes for you
Yours faithfuly
Li Ming