如何从vb.net中的查询字符串中获取数据列表

Question

<System.Web.Services.WebMethod()> _
Public Shared Function GetVehicleModels(ByVal vehicleval As String) As List(Of newvehicle)
    Return FillModels(vehicleval)
End Function
Public Shared Function FillModels(ByVal makeid As String) As List(Of newvehicle)

    Dim cnCos As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("SQLConnString").ConnectionString)
    Dim sqlCos As String = "Select VehicleModelName + ' ' + VehicleCC + ' CC' AS VMN, VehicleModelID FROM VehicleModels WHERE VehicleMakeId=0 OR VehicleMakeID = " & makeid & " ORDER BY VehicleModelName"
    Dim cmdCos As New SqlCommand(sqlCos, cnCos)
    cmdCos.CommandTimeout = MIS.DBTier.dbTimeOut
    cnCos.Open()

    cnCos.Close()
    cnCos = Nothing
    cmdCos = Nothing

End Function

我是开发领域的初学者。实际上在改变我想填写其他下拉我已经做了进一步如何我可以从查询字符串传递回传ajax数据。我的Ajax调用如下。

<script type="text/javascript">
    $(document).ready(function () {
        $("#ctl00_ContentPlaceHolder1_ddlMake").change(function () {
            alert("Hi");
            $.ajax({
                type: "POST",
                url: "newvehicle.aspx/GetVehicleModels",
                data: '{vehicleval: "' + $("#ctl00_ContentPlaceHolder1_ddlMake").val() + '" }',
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (response) {
                    $.each(response.d, function (key, value) {
                        $('#ctl00_ContentPlaceHolder1_ddlModel').append($("<option></option>").attr("value", value["_Id"]).text(value["_vehicleName"]));
                    });
                },
                failure: function (response) {
                    alert(response.d);
                }
            });

        });
    });


</script>