JSP 传参问题

[Y_kia]

<form action = "register_check.jsp" method = "post">
<table border = "1">
<tr>
<td>用户名</td>
<td><input type = 'text' name = 'id'></td>
</tr>
<tr>
<td>密码</td>
<td><input type = 'text' name = 'pass'></td>
</tr>
<tr>
<td>姓名</td>
<td><input type = 'text' name = 'name'></td>
</tr>
<tr>
<td><input type = 'submit' value = 'Submit'></td>
</tr>
</table>
</form>
out.println(request.getParameter("id"));//打印出来是null
这个问题是怎么回事的？