单项选择题
The pumps employed on board ship can be divided into two main categories ie（） pumps and centrifugal pumps.
A.gear
B.nonpositive displacement
C.positive displacement
D.rotary
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相关考题
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单项选择题
The pump has a constant stroke and the amount of fuel delivered is regulated by rotating （） which has a specially arranged helical groove cut into it.
A.the pump cylinder
B.the pump cam
C.the pump plunger
D.the pump miler -
单项选择题
The projection on a shaft designed to change circular motion into up and down or back and fore motion is called （）.
A.wheel
B.crankshaft
C.running gear
D.cam -
单项选择题
The process to remove exhaust gases by blowing in fresh air is called （）.
A.charging
B.supercharging
C.starting
D.scavenging
