namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Child2 s = new Child2();
            s.foo();
        }
    }
    class Base
    {
        public virtual void foo()
        {
            Console.WriteLine("base");
            bar();
        }
        public virtual void bar()
        {
            //hey I m here just for purpose, I know I m so reduntant
        }
    }
    class Child1 : Base
    {
        public override void bar()
        {
            Console.WriteLine("bar in child1");
        }
    }
    class Child2 : Child1
    {
        public override void foo()
        {
            Console.WriteLine("child2");
            base.foo();
        }
    }
}

child2
base
bar in child1