涡轮式发动机的反推是如何实现的
A. 改变发动机转向
B. 改变发动机进、排气方向
C. 改变发动机喷气方向
Which place in the turbojet engine is subjected to the highest temperature?
A. Compressor discharge.
B. Fuel spray nozzles.
C. Turbine inlet.
Which of the following is not the function of turbine?
A. transforming heat energy to mechanical energy.
B. make the air expand to work, so as to drive the compressor to work.
C. transforming mechanical energy to heat energy, and drive the compressor to work.
食品中总脂的测定方法可分为四类，统称为萃取法的有（）。
A. 直接萃取法
B. 减法测定法
C. 仪器法
D. 经化学处理后再萃取
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