Thank you very much, Bhaisahab and thedaffodils :)
Actually, I already know about the use of "etc" and "and so on", thedaffodils. I'm just a bit confused as somebody has told me it's not good to use them in formal writing. If possible, please follow this link and then tell me your idea:
No "etc" or "so on" in formal writing?
Many thanks
Newbie