Reusing existing classes and interfaces makes the job of programming easier. What are some of the future advantages that come from writing extendable base classes?

What will be an ideal response?

When you create a useful, extendable base class, you and other future programmers gain several advantages:
* Derived class creators save development time because much of the code that is needed for the class already has been written.
* Derived class creators save testing time because the base class code already has been tested and probably used in a variety of situations. In other words, the base class code is reliable.
* Programmers who create or use new derived classes already understand how the base class works, so the time it takes to learn the new class features is reduced.
* When you create a derived class in C#, the base class source code is not changed. Thus, the base class maintains its integrity.