<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<?php
include "nav.html";
include "a.html";
// include "b.html";
// include "c.html";
include "foot.html";
?>
</body>
</html>
这是我的index.php
我引入了导航栏nav.html,中间可以变换的a.html,页脚foot.html，当我点击导航栏的时候，出现对应的内容（也就是引入的a.html，b.html，c.html变化），请问大咖们这一块的逻辑应该怎么写
