phpcmsv9实现二级下拉菜单

<map>
      <ul id="nav">
         {pc:content action="category" catid="0" num="25" siteid="$siteid" order="listorder ASC"}
         <li><a href="{siteurl($siteid)}"><span>首页</span></a></li>
         {loop $data $k $v}
             <li><a href="{$v[url]}"{$v[catname]}</a>
             <ul>
                 {pc:content action="category" catid="$k" num="10" siteid="$siteid" order="listorder ASC"}
                 {loop $data $r}
                 <li><a href="{$r[url]}">{$r[catname]}</a></li>
                 {/loop}
                 {/pc}
            </ul>
        {/loop}
       {/pc}
     </ul>
   </map>