x
1
<select>
2
<optgroup label="分组 1">
3
<option>选项 1.1</option>
4
</optgroup>
5
<optgroup label="分组 2">
6
<option>选项 2.1</option>
7
<option>选项 2.2</option>
8
</optgroup>
9
<optgroup label="分组 3" disabled>
10
<option>选项 3.1</option>
11
<option>选项 3.2</option>
12
<option>选项 3.3</option>
13
</optgroup>
14
</select>
15