using System;

class BaseClass

{

    public string BaseProperty { get; set; }

}

​

class DerivedClass : BaseClass

{

    public string DerivedProperty { get; set; }

​

    public DerivedClass()

    {

        BaseProperty = "b";

        DerivedProperty = BaseProperty.ToUpper();

    }

    public BaseClass GetBase()

    {

        return this;

    }

}

​

public class Program

{

    public static void Main()

    {

        DerivedClass derivedClass = new DerivedClass();

        Console.WriteLine(derivedClass.DerivedProperty);

        Console.WriteLine(derivedClass.BaseProperty);

​

        BaseClass baseClass = derivedClass.GetBase();

        Console.WriteLine(baseClass.BaseProperty);

​

        BaseClass baseClass2 = derivedClass;

        Console.WriteLine(baseClass.BaseProperty);

    }

}