asp控制块不会让我嵌套一个代码块。有道理，但我该如何解决它

 <tr runat="server" >
   <th><%= Resources.bicweb_resources.BORDER_STYLE %></th>
   <td>
     <asp:DropDownList runat="server" id = "borderContent" class = "attribute" >
       <asp:ListItem value = "NULL">
       </asp:ListItem>
       <asp:ListItem value = "0" >
         <%= Resources.bicweb_resources.FALSE %>
       </asp:ListItem>
       <asp:ListItem value = "1">
         <%= Resources.bicweb_resources.TRUE %>
       </asp:ListItem>
     </asp:DropDownList>
   </td>
 </tr>
 <tr runat="server" >
   <th><%= Resources.bicw