Which statement is NOT true？
A. While displacement pump works, volume of the working chamber will increase and decrease alternately
B. A gear pump always has two gears
C. Any vane pump will have a rotor within a ring
D. A balanced vane pump has two outlet ports and they are positioned symmetrically
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The control mode in which tile final control element is moved from one of two fixed positions to the other is known as______.
A. dead band action
B. neutral zone action
C. range
D. on-off action
通货膨胀缺口是在什么情况下产生的？
A. 实际GDP大于潜在GDP
B. 实际GDP等于潜在GDP
C. 通货膨胀率低于潜在通货膨胀率
D. 价格水平超过均衡的价格水平
E. 潜在GDP大于实际GDP
Lubrication for the main reduction gears used with diesel engines is usually supplied by
A. oil from the main engine sump
B. an independent lube oil system
C. the stern bearing head tank
D. the stem bearing sump tank
_______型柴油机活塞顶部烧蚀不太严重时，可采用将活塞安装位置转动90°的方法，使之继续使用
A. Sulzer
B&W
C. MAN
D. UEC
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