add-on conference call的用法和样例：
- Cuartero regularly toted his favorite yo-yos in his suit pockets and in briefcases.He regularly spun two-handed while on conference calls.
- A 10% service charge is added on to the bill.
- The bank add on a 5% handling charge for changing traveller's cheque.
- The recommend method for using netmeeting in a conference call is to.
- My secretary bring the conference call notes.