日本原本出口制造品，进口原材料如粮食、石油。分析以下情况下Et本贸易条件的变化： a．中东战争使得石油供应紧缺。 b．韩国扩展了汽车的生产能力，并在加拿大和美国进行销售。 c．美国的工程师建立了核反应堆以代替石油燃料发电厂。 d．俄罗斯农业歉收。 e．日本降低牛肉和柑橘的进口关税。 Japan primarily exports manufactured goods，while importing raw materials such as food and oil．Analyze the impact on Japan's terms of trade of the following events： a．A war in the Middle East disrupts oil supply． b．Korea develops the ability to produce automobiles that it can sell in Canada and the United States． c．U.S. engineers develop a fusion reactor that replaces fossil fuel electricity plants． d．A harvest failure in Russia． e．A reduction in Japan's tariffs on imported beef and citrus fruit．