you can ask whatever you want, you give them ur student number, confirm your name and date of birth. then they ask you what subject eg maths, then the nature of the question eg annuities and they put you thrugh to a maths teacher who will already have been given all that info and they you just ask away. if your doing past hsc papers and get stuck its also really good because they have all the past papers there with them to go through questions with you. one of my school teaches said that last year he was on the phone to a student for 3 hours helping with past papers!