动态下拉框显示问题！

<tr class="firstalt"><td width="55%" height=25  id='submitrow'><p align="left">
         &nbsp;&nbsp;年级：<select size="1" name="grade_id" onChange="return goToPage()" onSelect="return goToPage()">  
         <option  value="0">年级选择</option>
<%
  String grade_id=(String)request.getAttribute("grade_id");
  if(grade_id==null)
  {
    grade_id="0";
  }
%>
<logic:iterate id="allgrade"  name="allgrade" type="com.ideacom.siis.domain.GradeInfo">
 <logic:equal name="allgrade" property="gradeId" value="<%=grade_id%>">
         <option value="<bean:write name="allgrade" property="gradeId"/>" selected><bean:write name="allgrade" property="gradeName"/></option>
  </logic:equal>
  <logic:notEqual name="allgrade" property="gradeId" value="<%=grade_id%>">
         <option value="<bean:write name="allgrade" property="gradeId"/>"><bean:write name="allgrade" property="gradeName"/></option>
  </logic:notEqual>
</logic:iterate>

     </select>
 班级：<select size="1" name="class_id" onChange="return goToPage()" onSelect="return goToPage()">
 <option  value="0">班级选择</option> 
<%
      String classid=(String)request.getAttribute("class_id");
  if(classid==null)
  {
    classid="0";
  }
   %>
<logic:iterate id="allclass"  name="allclass" type="com.ideacom.siis.domain.ClassInfo">

 <logic:equal name="allclass" property="classId" value="<%=classid%>">
         <option value="<bean:write name="allclass" property="classId"/>" selected><bean:write name="allclass" property="className"/></option>
  </logic:equal>
  <logic:notEqual name="allclass" property="classId" value="<%=classid%>">
         <option value="<bean:write name="allclass" property="classId"/>"><bean:write name="allclass" property="className"/></option>
  </logic:notEqual>
</logic:iterate> 

         </select> 
     学生：<select size="1" name="stdt_id"  onChange="return goToPage()" onSelect="return goToPage()">
         <option value="0">学生选择</option>
<%
      String stdtid=(String)request.getAttribute("stdt_id");
  if(stdtid==null)
  {
    stdtid="0";
  }   String msg_type=(String)request.getAttribute("msg_type");
  if(msg_type==null)
  {
    msg_type="0";
  }
   %>
<logic:iterate id="allstdt"  name="allstdt" type="com.ideacom.siis.domain.SendStdt">

 <logic:equal name="allstdt" property="stdt_id" value="<%=stdtid%>">
         <option value="<bean:write name="allstdt" property="stdt_id"/>" selected><bean:write name="allstdt" property="stdt_name"/></option>
  </logic:equal>
  <logic:notEqual name="allstdt" property="stdt_id" value="<%=stdtid%>">
         <option value="<bean:write name="allstdt" property="stdt_id"/>"><bean:write name="allstdt" property="stdt_name"/></option>
  </logic:notEqual>
</logic:iterate> 
         </select> 能看懂吗？？我这个可是有三个select互相递联的，完全可以满足你的要求
记得给分呦