将var传递给.load（ajax）php

Question

I have a php file that loads in the div ajax. I want to pass the php variable to that loaded php file.

        <?
        $post_id = get_the_ID();
        ?>

        <script>
        $(function() {
            $("body").click(function(e) {
                if (e.target.id == "contentblock" || $(e.target).parents("#contentblock").size()) {
                        //alert("Inside div");
                        if ($(e.target).is("a")) {
                            $('#afterdownload').fadeIn('slow');
                            $('#ajax').load('<?php echo get_template_directory_uri(); ?>/test.php');

                        }
                }
            });
        })   
        </script>

        <div id="ajax"></div>

This is how my test.php looks. The test.php loads but when I uncomment the include, which I want to use to pass the variable to this php, it doesn't show anything.

    <?
    //include 'single.php';
    ?>

    <p>You downloaded Post: <?php echo $post_id; ?></p> 

Answer 1

  $('#ajax').load('<?php echo get_template_directory_uri(); ?>/test.php?choices=<?php echo $post_id; ?>');

and in php file

$_GET['choices']