<!DOCTYPE HTML>
<html>
<body>
<table border="1">
<tr>
<th>一月 <dialog open>这是打开的对话窗口</dialog></th>
<th>二月</th>
<th>三月</th>
</tr>
<td>31</td>
<td>28</td>
</table>
</body>
</html>