Abstract types should not have public constructors

Microsoft's heading is a bit imprecise. Public will work , though. Private wont (though that has nothing to do with being abstract):

   class Program

    {

        static void Main(string[] args)

        {

            test2 t = new test2(); 

        }

    }

    public abstract class test

    {

       private  test()

        {

        }

    }

    public class test2 : test

    {

        public test2()

        {

        }

    }