In 21st Century, people from all over the world has gone through divers road of developement, they have different culture background, social system and concept of value, they keep divers lifestyle.我觉得发展道路，文化背景，社会制度，价值观念和生活方式都不用变复数，因为每个国家对应一种发展道路，文化背景，社会制度，价值观念和生活方式。如果你觉得哪里需要变复数自己变一下吧，每个人理解不同。