<div class="focus fl"> <a href="#" class="arrow-l"><</a> <a href="#" class="arrow-r"><i></i></a> <ul> <li><a href="#"><img src="upload/focus.jpg"></a></li> </ul> <ol class="circle"> <li class="current"></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ol> </div>改为bootstr轮播图

可以使用 Bootstrap 中的 Carousel 组件来实现轮播图，将原来的代码改为如下所示：

<div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
  <ol class="carousel-indicators">
    <li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
    <li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
    <li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
    <!-- 更多的 li 标签 -->
  </ol>
  <div class="carousel-inner">
    <div class="carousel-item active">
      <img class="d-block w-100" src="upload/focus.jpg" alt="First slide">
    </div>
    <div class="carousel-item">
      <img class="d-block w-100" src="upload/focus2.jpg" alt="Second slide">
    </div>
    <div class="carousel-item">
      <img class="d-block w-100" src="upload/focus3.jpg" alt="Third slide">
    </div>
    <!-- 更多的 div 标签 -->
  </div>
  <a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
    <span class="carousel-control-next-icon" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>

需要注意的是，Bootstrap 的 Carousel 组件需要引入相应的 JavaScript 和 CSS 文件。同时，需要根据实际情况修改图片路径和样式。