1)Suppose someone designed a stack abstract data type in which the func- tion top returned an access path (or pointer) rather than returning a copy of the top element. This is not a true data abstraction. Why? Give an example that illustrates the problem?

2)Describe a situation where a C# struct is preferable to a C# class?

3Explain the two problems with abstract data types that are ameliorated by inheritance?

4)What exactly does it mean for a subclass to have an is-a relationship with its parent class?