人们经常说收益递增的存在是国家之间产生摩擦的根源之一,因为每个国家都希望能扩大具有规模经济的行业的生产。依据垄断竞争模型和外部经济模型评述这观点。 It is often argued that the existence of increasing returns is a source of conflict between countries,since each country is better off if it can increase its production in those industries characterized by economies of scale.Evaluate this view in terms of both the monopolistic competition and the external economy models.