一：colspan：跨列屬性，同一行，跨多列
二：跨行屬性，rowspan
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<table border="6" width="500px" bgcolor="#f2f2f2" cellspacing="0" cellpadding="5" align="center">
<caption> 統計圖 </caption>
<thead>
<tr bgcolor="#2e8b57">
<th rowspan="2">城市</th>
<th colspan="2">2018</th>
<th rowspan="2">2019</th>
<th rowspan="2">2020</th>
</tr>
<tr bgcolor="#2e8b57">
<th>上半年</th>
<th>下半年</th>
</tr>
</thead>
<tbody align="center" valign="middle">
<tr>
<td bgcolor="#b8cce4">北京</td>
<td>8000</td>
<td>9000</td>
<td>10000</td>
<td>11000</td>
</tr>
<tr>
<td bgcolor="#b8cce4">上海</td>
<td>8001</td>
<td>9001</td>
<td>10001</td>
<td>11001</td>
</tr>
</tbody>
<tfoot align="center" valign="middle">
<tr>
<td height="30px" bgcolor="#b8cce4">合計</td>
<td>16001</td>
<td>18001</td>
<td>20001</td>
<td>22001</td>
</tr>
</tfoot>
</table>
</body>
</html>