小弟我有有关问题

interface man{    function talk();}abstract class person{    abstract function name();    abstract function age();    var $c="这是一个抽象类<br>";}class xiaoming extends person implements man {    function name(){        echo ("xiaoming<br>");    }    function age(){        echo ("12"."<br>");    }    function talk(){        echo ("love<br>");    }}class xiaoli extends person implements man{    var $mingzi;    function _construct($mingzi){        $this->mingzi=$mingzi;    }    function name(){        echo ($this->mingzi."<br>");    }    function age(){        echo ("13<br>");    }    function talk(){        echo ("you");    }}$p = new xiaoming();$p->name();$p->age();$p->talk();$x = new xiaoli("xiaoli");$x->age();$x->name();$x->talk();