Train the Trainer develops seminars and workshops for corporate training managers, who in turn train their employees. Your job at Train the Trainer is to put together the actual training materials. Right now, you are up against a deadline. The new object modeling seminar has a chapter on cardinality, and the client wants you to come up with at least three more examples for each of the four cardinality categories listed in Figure 6-16. The four categories are zero or many, zero or one, one and only one, and one or many. Even though you are under pressure, you are determined to use examples that are realistic and familiar to the students. What examples will you submit?