词汇与结构Normally, pressurization problems are caused by a malfunctioning of the pressure outflow or the pressure regulating valves _______, which allows the air to escape out of the pressurized cabin.

Currently, the frequently used methods for ampoule cleaning mainly include:( ) A: the alternating pressurized water and gas jet B: ultrasonic washing C: water-dumping washing methods D: Washing-free ampoule

The function of lubricating oil is to( ) A: maintain even distribution of bearing wear B: maintain a constant oil temperature C: maintain a pressurized fluid film between moving surfaces D: remove entrained water