Dear Li Ming:
I have heard that you have got trouble with your parents about weekend arrangement.
Surfing on internet won't bring you much benefit. However, it is a good way to relax since you just had a busy week. i do think it is important to negotiate with your parents about whether you should learn English and violin over weekend or just chill in your spare time.
In my opinion learning more about English and playing violin would be beneficial to you as long as you have got some spare time to relax yourself, in another word, do some surfing but not much, and go to the extra lesson or whateverit is.
Regard
XXX