Bootstrap4 网格系统错误

Bootstrap 4 Grid System Error

开始学习Bootstrap4和响应式网格系统。下面的代码是我的html。调整我的 window 大小时,所有列都可以正常工作,直到我达到 xs 屏幕尺寸,并且所有列自动跨越 12,而不是像我尝试做的那样跨越 4-4-4。尝试在线搜索,但似乎无法在任何地方找到答案。帮助表示赞赏。我已经添加了结束 html 标签,但由于某种原因它没有显示。

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>

            <div class="container">
                <div class="row">
                <div class="col-xs-4 col-sm-8 col-md-12 col-lg-4 box1">1</div>
                <div class="col-xs-4 col-sm-2 col-md-6 col-lg-4 box2">2</div>
                <div class="col-xs-4 col-sm-2 col-md-6 col-lg-4 box3">3</div>
                </div>
            </div>

        <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" 
        integrity="sha384-
        KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" 
        crossorigin="anonymous"></script>
        <script 
        src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper
        .min.js" integrity="sha384-
        ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" 
        crossorigin="anonymous"></script>
        <script 
        src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.
        js" integrity="sha384-
        JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" 
        crossorigin="anonymous"></script>

在 bootstrap 4 中没有 col-xs,取而代之的是你需要放一个 col-4 https://getbootstrap.com/docs/4.0/layout/grid/