abstract class A {
        private $name;
        function __construct($param){
            $this->name = 'liming'.'<br>';
        }
        function getName() {
            echo $this->name;
        }

        // 调用子类中的方法getAge2
        function getAge() {
            $this->getAge2();
        }

        function getAge3() {
            return '23';
        }
    }

class B extends A {
    function getAge2(){
        echo $this->getAge3();
    }
}

$a = new B('a');
$a->getName();
$a->getAge();