var data = BoshccEntities.Current.TB_MB_1

                .GroupJoin(BoshccEntities.Current.TB_MB_2, o => o.HospitalID, m => m.MemberID, (t, m) => new { t, m })

                .GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.ServiceCode, s => s.DicNum, (o, s) => new { t = o.t, m = o.m, s })

                .GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.PaymentMethodCode, p => p.DicNum, (o, p) => new { t = o.t, m = o.m, s = o.s, p })

                .Where(o =>

                    (isenable.HasValue ? o.t.IsEnable == isenable.Value : true)

                    && (hasHospital ? hospitalIDs.Contains(o.t.HospitalID) : true)

                    && (hasService ? o.t.ServiceCode == service : true)

                    && (hasPayment ? o.t.PaymentMethodCode == payment : true))

                .OrderBy(o => o.t.ID)

                .Select(o => new

                {

                    ID = o.t.ID,

                    HospitalID = o.t.HospitalID,

                    ServiceCode = o.t.ServiceCode,

                    PaymentMethodCode = o.t.PaymentMethodCode,

                    IsEnable = o.t.IsEnable,

                    Remark = o.t.Remark,

                    Hospital = o.m.FirstOrDefault(), //关键1

                    Service = o.s.FirstOrDefault(),

                    Payment = o.p.FirstOrDefault()

                })

                .ToList() //关键2

                .Select(o => new TB_MB_4

                {

                    ID = o.ID,

                    HospitalID = o.HospitalID,

                    ServiceCode = o.ServiceCode,

                    PaymentMethodCode = o.PaymentMethodCode,

                    IsEnable = o.IsEnable,

                    Remark = o.Remark,

                    HospitalName = o.Hospital == null ? "" : o.Hospital.HospitalName, //关键3

                    ServiceName = o.Service == null ? "" : o.Service.DicName,

                    PaymentName = o.Payment == null ? "" : o.Payment.DicName

                });