using System;

public class Program

{

    public static void Main()

    {

        var a = new A();

        var b = new B();

        Console.WriteLine(b.GetType() == typeof(A));

        Console.WriteLine(b is A);

    }

    class A {

        public int FieldA;

    }

    class B : A {

        public int FieldB;

    }

}