代码如下:
  <table  width="480" border="0" cellpadding="0" class="STYLE3" cellspacing="0" bordercolor="#ECE9D8" bgcolor="#FFFFFF">
           <tr>
          <td  class="STYLE3" scope="row">www</td>
          <td  class="STYLE3" scope="row">
         <select name="method" id="method" onchange="MM_jumpMenu('parent',this,0)">
              <option value="sss">aaa</option>
              <option value="www">bbb</option>
          </select></td>
        </tr>
    <fieldset id="tds0" style="display:none">   
          <tr>
          <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">ttt</td>
          <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">
            <input  name="user"  type="text" id="user"   /></td>
        </tr>
         <tr>
          <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">密码:</td>
          <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row"><span class="STYLE6">
            <input  name="pwd"  type="text" id="pwd"  /></span></td> 
        </tr> 
    </fieldset>  
  <fieldset id="tds1"  style="display:none">    
      <tr >
       <td  height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">IP地址:</td>
       <td  height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">
        <input  name="ip" type="text" id="IPstatic" size="16" maxlength="16" /></td>
      </tr>
     <tr >
         <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">DNS服务器:</td>
         <td height="30" align="left" bgcolor="#FFFFFF" class="STYLE3" scope="row">
         <input  name="dns1" type="text" id="IPdns1" size="16" maxlength="16" /></td>
         </tr> 
      </fieldset>  
  </tabe>
function MM_jumpMenu(targ,selObj,restore)

  var indx=selObj.selectedIndex;
  eval('document.getElementById("tds'+curmethod+'").style.display="none";');
  eval('document.getElementById("tds'+indx+'").style.display="";');
  curmethod=indx;