可通过增加size特性的值来将一个下拉列表框变成一个能显示多个选项的列表框。size特性的值应该是你希望一次显示的选项数量。
<!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>
<form action="http://www.example.com/profile.php">
<p>通过增加size特性的值来将一个下拉列表框变成一个能显示多个选项的列表框。</p>
<select name="instruments" size="3" multiple="multiple">
<option value="guitar"selected="selected">第一个</option>
<option value="drlue">第二个</option>
<option value="keyboard" selected="selected">第三个</option>
<option value="bass">第四个</option>
</select>
</form>
</body>
</html>