下拉框获取到的数据如何在input文本框中显示

１.*.html

<form name='upvalue' method="post" action="examSignup.jsp" target='_self'>
     <table><tr>
		<td width='1%'><input type=名称    name=sdname         value='' ></td>
		<select name=sop onchange=upall()>
         <option>18岁以下</option>
         <option>18-28岁</option>
         <option>28-38岁</option>
         <option>38岁以上</option>
        </select>
		


		</select>

		<td width='1%'><input type=hidden    name=sdcardid       value='' ></td>
	    <td width='1%'><input type=hidden    name=sdpostaddress  value='' ></td>
	    <td width='1%'><input type=hidden    name=sdqq           value='' ></td>
		<td width='1%'><input type=hidden    name=sdmail         value='' ></td>
	    <td width='1%'><input type=hidden    name=sdtel          value='' ></td>
	    <td width='1%'><input type=hidden    name=sdsex          value='' ></td>
		<td width='1%'><input type=hidden    name=sdcardtype     value='' ></td>
	    <td width='1%'><input type=hidden    name=sdclassid      value='' ></td>
	    <td width='1%'><input type=hidden    name=sdselftype     value='' ></td>
		<td width='1%'><input type=hidden    name=sdbirthday     value='' ></td>
		<td width='1%'><input type=hidden    name=sdyndoctor     value='' ></td>
		<td width='1%'><input type=hidden    name=sdedu          value='' ></td>
		<td width='1%'><input type=hidden    name=sdgradtime     value='' ></td>
	    <td width='1%'><input type=hidden    name=sdgradmajor    value='' ></td>
		<td width='1%'><input type=hidden    name=sdgradschool   value='' ></td>
		<td width='1%'><input type=hidden    name=sdexammajor    value='' ></td>
	    <td width='1%'><input type=hidden    name=sdclass        value='' ></td>
	    <td width='1%'><input type=hidden    name=sdcompany      value='' ></td>
	    <td width='1%'><input type=hidden    name=sdworkyear     value='' ></td>
		<td width='1%'><input type=hidden    name=sdjob          value='' ></td>
		<td width='1%'><input type=hidden    name=sdaddress      value='' ></td>
	    <td width='1%'><input type=hidden    name=sdworkterm1    value='' ></td>
	    <td width='1%'><input type=hidden    name=sdworkterm2    value='' ></td>
	    <td width='1%'><input type=hidden    name=sdauth         value='' ></td>
		<td width='1%'><input type=hidden    name=sdcompanycity  value='' ></td>
	    <td width='1%'><input type=hidden    name=sdexamtime     value='' ></td>
	   
	    <td width='1%'><input type=hidden    name='idadd'        value='add'></td>	 
	 </tr></table>
	 </form>
	
	 <script type="text/javascript">
		
		function upall(){
			   //alert('1');
			   document.upvalue.sdname.value=document.upvalue.sop.value;
			  
			   
			}
	 </script>

2.