The same year, the Federal Aviation Authority required that the boxes, which were never actually black, be painted orange or yellow to aid visibility.
同年，美国联邦航空管理局要求将这些实际上从未是黑色的盒子刷成橙色或黄色，以提高能见度。
Rough seas, limited visibility and a shortage of boats are slowing the delivery of disaster aid to the remote Indonesian islands of Mentawai, hit by a major earthquake and tsunami earlier this week.
汹涌的海浪、有限的能见度和船只的短缺延缓了向印尼偏远的明打威群岛输送救灾物资的努力。这个星期早些时候，该地区发生了严重的地震和海啸。
The observer sitting problem is important in terrain visibility analysis and is widely used in spatial information aid decision, telecom, and animal protection and so on.
观察点设置问题是地形可视性分析中的一类重要问题，在空间信息辅助决策、电信、野生动物保护等领域有着广泛的应用。
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