name = $name;  }  //抽象方法没有方法体{}  abstract public function hello();  abstract public function say();  public function test()  {    return 'Demo::test()';  }}class Demo1 extends Demo{  //必须在子类中全部实现父类中的抽象方法  public function hello()  {    return 'hello '.$this->name;  }  public function say()  {    return '我的name:'.$this->name;  }}$obj = new Demo1('php');echo $obj->hello();echo '
     
';echo $obj->say();