<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>W3Cschool教程(w3cschool.cn)</title>
<script>
function displayResult(){
document.getElementById("mySelect").multiple=true;
}
</script>
</head>
<body>
<form>
<select id="mySelect" size="4">
··<option>Apple</option>
··<option>Pear</option>
··<option>Banana</option>
··<option>Orange</option>
</select>
</form>
<button type="button" onclick="displayResult()">允许多个选择</button>
<p>按下Ctrl键来选择多个选项</p>
</body>
</html>
