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on board - n. in or on a plane, train, boat...
indicate - v. to show (something): to show that (something) exists or is true
source - n. someone or something that provides information
aviation - n. the business or practice of flying
certainty - n. a fact about which there is no doubt
classified - adj. kept secret from all but a few people in government
merciful - adj. Kind and forgiving; not cruel or harsh; having or showing mercy
prefer - v. to like better or best
sanctions - n. economic or military measures designed to force a nation to do something or stop doing something
participate - v. to take part
preliminary - adj. coming before the main part of something
