<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.c1{
200px;
height: 200px;
float: left;
}
.c2{
200px;
height: 200px;
background-color: green;
/*float:left左 right右*/
float: left;
}
.c3{
200px;
height: 200px;
/*clear:left左 right右 both左和右都*/
float: left;
clear: both;
}
.c4{
200px;
height: 200px;
background-color: yellow;
float: left;
}
</style>
</head>
<body>
<div class="c1"></div>
<div class="c2"></div>
<div class="c3"></div>
<div class="c4"></div>
</body>
</html>