在创建了下面这样的自定义帖子类型之后，我仍然没有任何选项来设置帖子的父级，我是否遗漏了什么？

register_post_type(
  \'projects\',
  array(
    \'labels\' => array(
      \'name\' => \'Projects\',
      \'singular_name\' => \'Project\'
    ),
    \'public\' => true,
    \'capability_type\' => \'post\',
    \'supports\' => array(\'title\', \'editor\', \'thumbnail\', \'excerpt\', \'comments\'),
    \'hierarchical\' => true,
    \'menu_position\' => 5
  )
);