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>
    <form>
        <select>
            <option value="">请选择：</option>
            <optgroup label="水果">
                <option value="apple">苹果</option>
                <option value="bannana">香蕉</option>
                <option value="watermelon">西瓜</option>
            </option>
            <optgroup label="蔬菜">
                <option value="xhs">西红柿</option>
                <option value="lg">南瓜</option>
                <option value="dg">冬瓜</option>
            </option>
        </select>
    </form>
    
</body>
</html>