如何让回车键实现TAB键的功能啊

<script language="javascript" type="text/javascript">
function   focusMove(obj,evt)//加OBJ是为了适应火狐浏览器的效果   


  {


          var   e   =   document.activeElement;


          if(e.tagName   ==   "INPUT"   &&   (


                e.type   ==   "text"           ||   


                e.type   ==   "password"   ||   


                e.type   ==   "checkbox"   ||   


                e.type   ==   "radio")       ||


                e.tagName   ==   "SELECT"


              )


          {


             evt=evt?evt:window.event;
                  if(evt.keyCode   ==   13)   //按下enter键
                  {


                  window.event?evt.keyCode=9:obj.nextSibling.nextSibling.focus();//多加一个nextSibling是因为火狐把换行也当做一个节点看待!
                  }


                            }


  }  


</script>

<form name="form1" id="form1">
<a href="#" onClick="AddInput()">上传一个</a>
<input type="text" onkeydown="focusMove(this,event)">
<input type="password" onkeydown="focusMove(this,event)">
<select  name="picclass"  size="1">
              <option value='1' selected >金融保险 </option>
              <option value='2'>交通运输  </option>
              <option value='3'>文艺体育  </option>
              <option value='4'>邮电通讯  </option>
            


</select>

</form>