单项选择题
The is employed to warm up a large diesel engine before its starting（）
A.hot air
B.hot boiler water
C.cylinder water
D.hot seawater
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相关考题
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单项选择题
In slow speed two-stroke engines,（）the fresh air entering begins when and stops as（）
A.the inlet port is opened by the up coming piston； the port is closed by the down going
B.the inlet valve is opened by the down going piston；the inlet valve is closed
C.the inlet port is opened by the down going piston；the port is closed by the up coming
D.the inlet valve is opened -
单项选择题
Usually we take the cooling effect of the air flown through the cylinder during the overlap period as（）
A.inevitable
B.harmful
C.helpful
D.unacceptable -
单项选择题
When the air charge contacts with the cylinders and pistons and mixes with the residual gases, it will（）
A.increase in temperature
B.lose its energy partly
C.expand and do work
D.begin to be compressed
