输出的内容里怎样去掉多余的代码，只把输出语句中的内容输出来
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>php语句结束符</title>
</head>
<body>
<p>
<?php
echo "欢迎同学们！";
echo "<br/>";
echo "Welcome" . " to imooc!";
echo "<br/>";
echo 1+2+3+4+5;
?>
</p>
</body>
</html>
我的输出内容：
<pre><!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>php语句结束符</title> </head> <body> <p> 欢迎同学们！Welcome to imooc!15</p> </body> </html>
