likewise, services or intangible products are just as relevant to the definition, marketing research, and so on all play a very significant role in improving the trade balance of the united states.
与此相似,这一定义同样涵盖了各种服务或者无形产品,因为航班服务、财务服务、广告服务、管理资讯、营销研究等等,在美国的贸易平衡中都起到非常重要的作用。