jsp按钮时出现了这样的问题求大神指教!!急!

只有第一个按钮可以显示答案,第二个就显示不了了,怎么办啊图片说明
去掉 display=“none”后这样显示图片说明

<%@ page contentType="text/html; charset=gb2312" language="java" %>
<%@ page import= "com.mingrisoft.action.Examination" %>
<%@ page import= "com.mingrisoft.dao.ExaminationDAO" %>
<%@ page import= "java.util.ArrayList" %>
<%@ taglib prefix= "c" uri = "http://java.sun.com/jsp/jstl/core" %> 

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>试题库管理系统</title>
<link href="CSS/style1.css" >
<%
     ArrayList<Examination> users = new ExaminationDAO().getAllExaminationInfos();
     if (users == null) {
         users = new ArrayList<>();
     }
     %>
</head>
<body>
   <div class="bgStyle">
        <div class="header">
            <div class="logo">
                <img src="Images/logo.png">
            </div>          
            <!--注释:清除div的浮动-->
            <div class="clear"></div>
        </div>
    </div>
   <!--  <table border="1" style="text-align: center; border-collapse: collapse">-->


   <table width="1102" height="266" border="0" align="center" cellpadding="0" cellspacing="0">
        <tr>
             &nbsp;
        </tr>
        <% 
           for (Examination sa : users) {
        %>        
        <tr>

            <td ><%=sa.getSubject() %>(<%=sa.getType() %>)
               <input type="button" value="显示答案" id="test">
                 <div id="testDiv" style="width:100px; height:100px; border:1px solid red; display:none;"> <%=sa.getAnswer() %> </div>
            </td>  

            <tr >
               <td> &nbsp;&nbsp;&nbsp;A.<%=sa.getOptionA() %> </td>             
            </tr>

            <tr> 
               <td> &nbsp;&nbsp;&nbsp;B.<%=sa.getOptionB() %> </td>
            </tr>

            <tr>  
               <td> &nbsp;&nbsp;&nbsp;C.<%=sa.getOptionC() %> </td>             
            </tr>

            <tr>
               <td> &nbsp;&nbsp;&nbsp;D.<%=sa.getOptionD() %> </td>
            </tr> 

            <tr>
               <td> &nbsp; </td>
            </tr> 

        </tr>
      <% } 
       %>
    </table>
</body>
<script type="text/javascript">
     document.getElementById("test").onclick=function(){
      document.getElementById("testDiv").style.display="inline";
     }
</script> 
</html>

id始终选择第一个。建议加上传入值来区分。

循环渲染之后,页面会出现多个相同的id,导致浏览器无法加载,可以在id后面拼接上下标。