??      function002.php     
<html>
<head>
<title>7 ?????</title>

<style>
.back1{
background-color: yellow;
}
</style>

</head>

<body>
<h1>7.2 ?????</h1>

<?php
function test($a){ #???????????????????$a???????
echo "<h1 class =\"back1\">$a</h1>\n";
}

test("????");#test???????????????
test("?????");#test????????????????
test("?????");#test????????????????

?>

</body>
</html>