<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<style type="text/css">
body {
background-image: url("pic/main_background_color.jpg");
}
</style>
</head>
<body>
<form action="doAction.php?act=adduser"method ='post'>
<img src="logo.jpg" width="625" height="180" alt=""/>
<div align="center">
<h1 style="color: aliceblue;position:relative;top:70px;font-size: 60px" >用户注册</h1></div>
<div align="center">
<h3 style="color: aliceblue;position:relative;top:70px;font-size: 60px" > 姓名：
<input type="text" name= "stuName" id="btn" value="" placeholder="姓名" required='required' style="position: relative;top: 0px;width: 400px;height: 60px;font-size: 60px;color: #000000;background: #FCFCFC;">
</h3>
<h3 style="color: aliceblue;position:relative;top:70px;font-size: 60px" > 学号：
<input type="text" id="btn" name= "stuID" value="" placeholder="学号" required='required' style="position: relative;top: 0px;width: 400px;height: 60px;font-size: 60px;color: #000000;background: #FCFCFC;">
</h3>
<h3 style="color: aliceblue;position:relative;top:70px;font-size: 60px" > 密码：
<input type="password" name= "stuPwd" id="btn" value="" placeholder="密码" required='required' style="position: relative;top: 0px;width: 400px;height: 60px;font-size: 60px;color: #000000;background: #FCFCFC;">
</h3>
<h3 style="color: aliceblue;position:relative;top:70px;font-size: 60px" >身份证：
<input type="text" name= "stuRID" id="btn" value="" placeholder="身份证" required='required' style="position: relative;top: 0px;width: 400px;height: 60px;font-size: 60px;color: #000000;background: #FCFCFC;">
</h3>
</div>
<div align="center">
<input type="submit" value="提交" style="position: relative;top: 80px;left: 0px;width: 200px;height: 80px; background: #FFFFFF;font-size: 50px">
<a href="main.html">
<input type="button" value="返回" class="inputbox" style="position: relative;top: 80px;left: 0px;width: 200px;height: 80px; background: #FFFFFF;font-size: 50px"></a></div>
<script type="text/javascript" >
var oBtn = document.getElementById('btn');
var k=0;
function apply(){
}
</script>
</body>
</html>
方法的类型不对
type类型有问题，