```html <ul class="nav nav-tabs"> <li class="active"><a href="#">苹果</a></li> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">小米 <span class="caret"></span></a> <ul class="dropdown-menu" > <li><a href="#">小米手机</a></li> <li><a href="#">小米电脑</a></li> <li><a href="#">小米平板</a></li> </ul> </li> <li><a href="#">华为</a></li> </ul> ```