console 命令行工具 X clear
console
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>下拉菜单练习</title>
</head>

<body>
    <form>
        下拉菜单：<br>
        <select name="请选择">
            <option value="qxz">请选择</option>
            <optgroup label="水果">
            <option value="pg">苹果</option>
            <option value="mht">猕猴桃</option>
            <option value="xz">杏子</option>
        </optgroup>
            <optgroup label="蔬菜">
            <option value="xhs">西红柿</option>
            <option value="bc">白菜</option>
            <option value="ymc">油麦菜</option>
        </optgroup>
    </select>
    </form>
</body>

</html>