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<!doctype html>
<html>
<head>
<title>抛物运动</title>
<meta charset="utf-8" />
<style type="text/css">
*{padding:0;margin:0;}
body{font-size:13px;padding:10px;}
p{margin:2px;}
.wrap{position:relative;width:1000px;height:550px;margin:0 auto;border:1px solid #ccc;margin-top:50px;}
#fall{width:20px;font-size:1px;height:20px;background:#000;position:absolute;top:0;left:0;}
</style>
</head>
<body>
<h3>模拟重力状态下的抛物运动(假使1px==1mm)</h3>
CSS代码...
JS代码...
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