namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 2008;
            Program .switchvalue (i);
            Console.Read();
        }
        static void switchvalue(i)
        {
            switch (i)
            {
                case 2008:
                case 2009:
                    {
                       i++;break ;
                    }
                case 2010:i--;break ;
            }
        }
    }
}

namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 2008;
            Program .switchvalue (i);
            Console.Read();
        }
        static void switchvalue(int i)
        {
            switch (i)
            {
                case 2008:
                case 2009:
                    {
                       i++;break ;
                    }
                case 2010:i--;break ;
            }
        }
    }
}

感谢了！

2楼已经改过来了