From 2002-2004, I was the Chief Leader and Vice-President for the Student Association.
我不知道香港 點叫領袖生 , so I put chief leader. I thought `Prefect' is for風 紀 .
For 班會副主席 , is it only for your class or for the whole grade?
If for your class only, then use: class association.
If for the whole grade, you can use student association or student council.
You might not like my `wording', but it doesn't matter, NO hard feeling. Because I found the English language in Hong Kong is somewhat different from our English language. Maybe this is the difference between English-English and American-English.
I during 02-04 years, , have ever held the post of leader to get in the school and class would vice- chairman. {I during 02-04 years, , have ever held the post of leader and got in the school and class would vice- chairman.}