Linq语句AsEnumerable()的使用

List<CoupleBackList> CoupleBackList_at = new List<CoupleBackList>();

var retData = RetDataList.AsEnumerable().Select(t => new
                {
                    Id = t.Field<Guid>("Id"),
                    QText = t.Field<string>("QText"),
                    ManagerName = t.Field<string>("ManagerName"),
                    Name = t.Field<string>("Name"),
                });

foreach (var item in retData)
            {
                CoupleBackList_at.Add(new CoupleBackList
                {

                    Id = item.Id,
                    QText = item.QText,
                    ManagerName = item.ManagerName,
                    Name = item.Name,
                });
            }

        public class CoupleBackList
        {
            /// <summary>
            /// 问题反馈ID
            /// </summary>
            public Guid Id { get; set; }
            /// <summary>
            /// 问题描述
            /// </summary>
            public string QText { get; set; }

            /// <summary>
            /// 发起人
            /// </summary>
            public string ManagerName { get; set; }

            /// <summary>
            /// 所在单位
            /// </summary>
            public string Name { get; set; }

        }