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>Document</title>
</head>

<body>

    <body>
        <select>
            <option value="">请选择</option>
            <optgroup label="水果">
                <option value="apple">苹果</option>
                <option value="nht">猕猴桃</option>
                <option value="xz">杏子</option>
            </optgroup>
            <!---------->
            <optgroup label="蔬菜">
                <option value="xhs">西红柿</option>
                <option value="ba">白菜</option>
                <option value="ymc">油麦菜</option>
        </select>
    </body>
</body>

</html>