Ted,
I think you understand. This discussion became more generic.
In some models described here, like that using two interfaces, you can only have one instance (class Coach) that works like Trainer and Student since Interface as well as abstract class can not be instanciated. Other model suggests that your Coach object can be either a Student or a Trainer as explained before.
Actually, the first question asks for the "and", not "or" condition.
A tennis coach is a student and a trainer?
Adrian