HTML page post to PHP, why did it become a php download instead of a PHP page?

Phphtml

Just started learning PHP
This is an HTML page

Please fnish it

Name:mrmrsms

Email Address:

Response:this is ... excellentokayboring

Comment:

PHP page

$title =$_post[' title ';
$name =$_post[' name '];
$response =$_post[' response '];
$comment =$_post[' comments '];
Print "

Thank, $title $name, for your comments

";
?>

I can't change post to get. Using XAMPP, when testing PHP pages alone, can be displayed, or is there a problem with the environment configuration?

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