单项选择题
A.at high speed and full load
B.at low speed and part load
C.when heavy fuel oil is used at sea
D.when the ships run long distance
单项选择题 A common rail engine has only one or two high pressure pumps in operation at the same（）time, and the injection into each cylinder.
单项选择题 （）uses one or two high pressure pumps for all the cylinders with one more standby, while（）have a separate high-pressure pump for each cylinder.
单项选择题 In a common rail engine, the fuel is injected into cylinders（）