<th>元素和<td>元素的用法一样，但它的作用是表示列或行的标题
<!DOCTYPE html>
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<html>
<head>
<title>TODO supply a title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<div>TODO write content</div>
<table>
<tr>
<th></th>
<th scope="col">标题</th>
<th scope="col">标题</th>
</tr>
<tr>
<th scope="row">标题</th>
<td内容</td>
<td>内容</td>
</tr>
<tr>
<th scope="row">标题</th>
<td>内容</td>
<td>内容</td>
</tr>
</table>
</body>
</html>