Dear Sir/Mrs:
I'm Lihua from Xinhua Middle School. The propose of this letter is to give you an advice about the topic of online debate activity.
In my opinion, the topic can be "thanksgiving". There are two reasons. First of all, today some teenagers forget the idea of thanksgiving. They take the love of parents, teachers, friends as granted, so it is necessary to remind them how important of thanksgiving. Second, there is a festival named "thanksgiving Day". You can introduce the source and meaning of this festival.
Hope the activity can be succeed.
Your sincerely,
Lihua