How do I approach my BOSS about this??????

My boss sent me on a weeks worth of training out of state in an effort to teach me everything I DON’T know about our companies main system. There's an employee here the hardly ever shows up & I KNOW this “trip” originally stemmed from this problem. While I was gone & ever since I have been back this employee has arrived way before time, & has been working away vigorously @ his/her work, which is TOTALLY abnormal!! Mind you, this absenteeism has been going on for about a decade (literally). I don’t know how to ask my boss if I am going to get to do the things I have learned (which was a lot of little different things) so as NOT to FORGET. Repetition is the main key in all the things I learned… I just don’t know what to say to my boss. I don’t want to sound like I am in a hurry to get this person out the door. What is a nice way to ask him if I am going to start doing the things I learned without being too demanding or seemingly aggressive/bossy?? HELP!!!