使用ASP.NET和C＃在ListBox中选择多个值

Question

为什么“SelectedValue”仅选择多选模式中的第一个值？

ListTag.SelectedValue = "Tag1"; <-- only this is selects
ListTag.SelectedValue = "Tag2";

angular.module("test",[]).controller("testc",function($scope) {   
      $scope.data=[{"typetext": "0","role": "User"},{"typetext": "1","role": "Admin"}]; });