<form action="/test.php">
<label for="douong">Chọn đồ uống:</label>
<select name="douong" id="douong">
<optgroup label="30k">
<option value="cafe">Cà phê</option>
<option value="nuoccam">Nước cam</option>
</optgroup>
<optgroup label="10k">
<option value="trada">Trà đá</option>
<option value="nuocloc">Nước lọc</option>
</optgroup>
</select>
<br><br>
<input type="submit" value="Xác nhận">
</form>
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