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单选题
气源系统提供增压空气，用于空调：the pneumatic system provides pressurized air for air-conditioning:
A
反推操作和防冰thrust reverse operation and anti-icing
B
发动机起动和防冰 engine starting and anti-icing
C
地面减升和发动机起动 ground lift dumping and engine starting
D
应急起落架放出和发动机起动 emergency gear extension and engine starting
答案解析
正确答案：B
