29.飛機的總阻力是_______,但慢慢降低到最小然後在高速時再次增加 (A)在所有飛機速度中都是恆定不變 (B)低速時較低 (C)高速時較低 (D)低速時較高

5. If an aircraft is operating at 40,000 ft. the pressurization ensures that (A)sea level pressure is maintained in the cabin. (B)the cabin pressure is progressively increased until the operational height is reached. (C)the cabin pressure above 10,000 ft. (D)the cabin pressure is equivalent to an altitude of less than 10,000 ft.