html 9_16
<html>
<head>
<title>标题标记实验</title>
<meta http-equiv="Content-Type"
content="text/html; charset=utf8">
</head>
<h1 align="center">一级标题居中</h1>
<h2 align="right">二级标题右对齐</h2>
这是普通文字！！
<h3 align="left">三级标题左对齐</h3>
<h4>四级标题</h4>
</body>
</html>