                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /JavaScript入門篇

一個鍵都運行不了，大神們幫忙看看

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" Content="text/html; charset=utf-8" />
<title>javascript</title>
<style type="text/css">
body{font-size:12px;}
#txt{
??? height:400px;
??? width:600px;
?? ?border:#333 solid 1px;
?? ?padding:5px;}
p{
?? ?line-height:18px;
?? ?text-indent:2em;}
</style>
</head>
<body>
? <h2 id="con">JavaScript課程</H2>
? <div id="txt">
???? <h5>JavaScript為網頁添加動態效果并實現與用戶交互的功能。</h5>
??????? <p>1. JavaScript入門篇，讓不懂JS的你，快速了解JS。</p>
??????? <p>2. JavaScript進階篇，讓你掌握JS的基礎語法、函數、數組、事件、內置對象、BOM瀏覽器、DOM操作。</p>
??????? <p>3. 學完以上兩門基礎課后，在深入學習JavaScript的變量作用域、事件、對象、運動、cookie、正則表達式、ajax等課程。</p>
? </div>
? <form>
? 
??? <input type="button" value="改變顏色" > ?
??? <input type="button" value="改變寬高" >
??? <input type="button" value="隱藏內容" >
??? <input type="button" value="顯示內容" >
??? <input type="button" value="取消設置" >
? </form>
? <script type="text/javascript">
??? var mytxt=document.getElementById("txt");
//定義"改變顏色"的函數
??? function changecolor()
??????? {
??????????? mytxt.style.color="red";
??????????? mytxt.style.blackgroundColor="#ccc";
??????? }
//定義"改變寬高"的函數
??? function changesize()
??????? {
??????????? mytxt.style.width="300px";
??????????? mytxt.style.height="300px";
??????? }
//定義"隱藏內容"的函數
??? function hidetext()
??????? {
??????????? mytxt.style.display="noen";
??????? }
//定義"顯示內容"的函數
??? function showtext()
??????? {
??????????? mytxt.style.display="block";
??????? }
//定義"取消設置"的函
??? function resttext()
??????? {
??????????? var resttext=confrim("確認取消嗎？")
???????????? if(resttext==ture)
??????????????? {
??????????????????? txt.removeAttribute('style');
??????????????? }
??????? }

? </script>
</body>
</html>