求教为何我写了align="center"后下面那两个按钮仍然没有居中
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<table border="1">
<caption>信息注册页面</caption>
<tr>
<td>用户名:</td>
<td><input type="text"class=text;size="12"maxlength="20";name="username></td>
</tr>
<tr>
<td>密码:</td>
<td><input type="password";size="12"maxlength="20";name="youpw"></td>
</tr>
<tr>
<td>确认密码:</td>
<td><input type="password";size="12"maxlength="20";name="youpw"></td>
</tr>
<tr>
<td>性别</td>
<td><input type="radio" value="male"/>男
<input type="radio" value="female"/>女</td>
</tr>
<tr>
<td>技术</td>
<td><input type="checkbox" name="java" />java
<input type="checkbox" name="jsp" />jsp
<input type="checkbox" name="html"/>html
</td>
</tr>
<tr>
<td>国家</td>
<form>
<td><select name="fruit" size="1">
<option value="Country1">中国</option>
<option value="Country2">美国</option>
<option value="Country3">英国</option>
<option value="Country4">法国</option>
<option value="Country5">印度</option>
</select>
</form>
</tr>
<tr>
<td align="center"><input type="submit"value="提交"/>
<input type="reset" value="重置"/>
</td>
</tr>
</table>
</html>
求教为何我写了align="center"后下面那两个按钮仍然没有居中
echo_kinchao
疯狂的程序猿z