php中的global及GLOBALS的一些有关问题

$a = 'scnjl';

function test() {
	global $a;
	unset($a);
}

test();
var_dump($a);

function test1() {
	unset($GLOBALS['a']);
}

test1();
var_dump($a);

include 'test009.php';

Class A {
	var $name;

	function __construct() {

	}

	function A() {
		$this->__construct();
	}

	function test() {
		var_dump($GLOBALS['var']);
	}

	function test1() {
		$this->test();
	}
}

$a = new A();

$var = 'scnjl';

class xx {

	function __construct() {

	}
	
	function test() {
		include 'test008.php';
		$a->test1();
	}
}

$xx = new xx();

$xx->test();