大专及以上学历，航空航天，工程或航天发动机专业。
College degree or above majoring in aerospace, engineering or aerospace engine.
航天飞机发动机内的这三个阀门不断被更换，以确保它们是最有效的，能保障飞行的安全。
The three valves in the shuttle's engine compartment kept being replaced to ensure they were the best available and safe to fly.
航天飞机的发动机和耐热瓷砖防止其再重返大气层时被烧坏，但是维护成本也很昂贵，而分配不同承包人的任务时又增加了开销。
The shuttle’s engines and the tiles that protect it from the heat of re-entry proved expensive to maintain, and divvying up work among different contractors added to the costs.
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