ASP.NET下拉修改

<asp:DropDownList ID="dropOrder" runat="server" AutoPostBack="True" OnSelectedIndexChanged="dropOrder_SelectedIndexChanged">
                                            <asp:ListItem Value="priceLowToHigh">价格从低到高</asp:ListItem>
                                            <asp:ListItem Value="priceHighToLow">价格从高到低</asp:ListItem>
                                            <asp:ListItem Value="mileageLowToHigh">数字从低到高</asp:ListItem>
                                            <asp:ListItem Value="mileageHighToLow">数字从高到低</asp:ListItem>
                                        </asp:DropDownList>


上面是个下拉选择框请问高手们要怎么改成不是下来的。谢