<html>
<body>
<form action="http://ziqiangxuetang.com/tags/demo_form.asp">
<select required>
� <option value="volvo">Volvo</option>
� <option value="saab">Saab</option>
� <option value="mercedes">Mercedes</option>
� <option value="audi">Audi</option>
</select>
<input type="submit">
</form>
<p><b>Note:</b> The required attribute is not supported in any of the major browsers.</p>
</body></html>