public class Lookup
    {
        public static int pid;
        public static string description;
        public int PID
        {
            get
            {
                return this.pid;
            }
        }        public string Description
        {
            get
            {
                return this.description;
            }
            set
            {
                if(this.description!=value)
                this.description = value;
            }
        }
    }
设置成静态的。就行了