专注前端素材！
源代码：
点击运行
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>素材8网教程(study.sucai8.cn)</title> </head> <body> <select> <optgroup label="Swedish Cars"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> </optgroup> <optgroup label="German Cars"> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </optgroup> </select> </body> </html>
运行结果