public interface classA        {            string User            {                get;                set;            }        }public interface classB        {            string User            {                get;                set;            }        }public interface facs : classA, classB        {        }public class classC{      public facs dd;}classC c = new classC();c.dd.User = "dd";錯誤：Error 2 Ambiguity between 'classA.User' and 'classB.User' 這類問題如何解決？問題原型在一個系統dll中