使用关键字 extends

     name=$name;            $this->age=$age;            $this->sex=$sex;        }        function say(){            echo '我的名字：',$this->name,'我的性别是',$this->sex,'我的年龄是',$this->age;            echo '
';        }        function run(){            echo $this->name,'正在走路';            echo '
';        }    }class stu extends person{    var $school;    function study(){        echo $this->name,'正在',$this->school,'学习';        echo '
';    }}class teacher extends stu{    var $wage;    function teaching(){        echo $this->name,'正在',$this->school,'教书','每月工资是',$this->wage;    }}$teacher1= new teacher('张三','男',40);$teacher1->school='edu';$teacher1->wage=5000;$teacher1->say();$teacher1->run();$teacher1->teaching();/*打印结果是：我的名字：张三我的性别是男我的年龄是40张三正在走路张三正在edu教书每月工资是5000*/?>