单选题Some vessels are equipped with a water lubricated stern robeWhen at sea, operating under normal conditions, the water service valve from the ships saltwater system to the bearing should be （）.Aclosed, and no leakage permitted across the shaft packingBclosed, and only slight leakage permitted across the shaft packingCopen, and no leakage permitted across the shaft packingDopen, and only slight leakage permitted across the shaft packing
单选题
Some vessels are equipped with a water lubricated stern robeWhen at sea, operating under normal conditions, the water service valve from the ships saltwater system to the bearing should be （）.
A
closed, and no leakage permitted across the shaft packing
B
closed, and only slight leakage permitted across the shaft packing
C
open, and no leakage permitted across the shaft packing
D
open, and only slight leakage permitted across the shaft packing
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