Dear Lan Lan,
We haven't been in touch for a little while now and very glad to have recieved your letter this morning. Also happy to find that you are keeping very well. In the letter you told me that your class has computer lessons now and you are so fond of it. Unfortunately, you seem to have addicted to surfing of the internet and doing it while attending your computer lessons and is distractting you from listening to your teacher of teaching you how to make use of the computer instead.
Well, I think this may be a very common problem for many of us. It is actually just a matter of will power, which you need to overcome it yourself. All you have to do is to tell yourself how important that learning is and make learning your priority. Make sure that you must do your school works before all other things, don't go on line until you have done so. keep to this principle in mind and you will have more concentration during classes.
Hope I am giving a useful suggestion and you will soon doing better and with less distracttion. Best wish, and please write to me more often!
A best friend of yours,
Li Dong
很高兴能够帮到你,希望会令你满意.