using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{
    public class A
    {
        public virtual event EventHandler SomeEvent;
        public A()
        {
            SomeEvent += new EventHandler(OnSomeEvent);
        }

        void OnSomeEvent(object sender, EventArgs e)
        {
            Console.WriteLine("SomeEvent raised!");
        }
    }
    public class B : A
    {
        public override event EventHandler SomeEvent;
        public void PerformSomeEvent()
        {
            if (SomeEvent != null)
                SomeEvent(this, EventArgs.Empty);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            B b = new B();
            b.PerformSomeEvent();
        }
    }
}