写法:
<div><img src="二维码图片的路径.jpg" /></div>
<!DOCTYPE html><html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
img{
position:absolute
}
.m2{
display: none
}
li:hover > .m2{
display: inline
z-index: 10
}
</style>
</head>
<body>
<ul>
<li>
<img class="m1" src="xx.jpg">
<img class="m2" src="2.jpeg">
</li>
</ul>
</body>
</html>
大概就这样