在小型，中型，大型等不同设备上，如果要将元素向左浮动，请使用float-*-left类。
以下是您可以使用的类-
Small Devices: float-sm-leftMedium Devices: float-md-leftLarge Devices: float-lg-left
让我们看一个示例，将元素浮动到不同屏幕的左侧-
<!DOCTYPE html> <html lang="en"> <head> <title>Bootstrap Example</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css"> <script src="https://cdn.staticfile.org/jquery/3.3.1/jquery.min.js"></script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script> </head> <body> <div class="container"> <h2>Demo</h2> <div class="clearfix"> <div class="float-sm-left">This text is on the left (on small screen).</div><br> <div class="float-md-left">This text is on the left (on medium screen).</div><br> <div class="float-lg-left">This text is on the left (on large screen).</div><br> <div class="float-xl-left">This text is on the left (on extra large screen).</div><br> </div> </div> </body> </html>