public ActionResult ExchangeListRefresh(string ExchangeID)         {             string strExchangeID = ExchangeID.Substring(0, ExchangeID.Length - 1);             GTSoft.Web.BusinessService.DataExchangeService pDataExchangeService =                          new GTSoft.Web.BusinessService.DataExchangeService(_pLoginedInfo);             DataTable dt = pDataExchangeService.GetExchangeRate(strExchangeID);             return Json(dt);         }前臺↑dt中是只有一個字段ExchangeRate的數據，有三個值{100,100,80}。我要怎么樣讓他傳到前臺，然后前臺接收之后遍歷出來，我現在寫得return Json(dt);會報錯，說“獲取后臺數據出錯，請刷新頁面后再嘗試！”