How do you unlock extra levels in super monkey ball

To unlock Beginner Extras, you need to complete all of Beginner without losing a life. To unlock Advanced Extras, you also need to complete all of Advanced without losing a life (it's pretty hard). However, to unlock Expert Extras, you need to do all of Expert without losing a CONTINUE. And to unlock the Master stages, you need to do all of Expert and Expert Extras without losing a continue.