单项选择题
A.open；the minimum components
B.open；the high cooling efficiency
C.central；there are more coolers and a extra set of pumps
D.central；there is only one component contacts seawater
单项选择题 An alarm device inserted between the deaerating tank and the expansion tank can notify the on-watching crew that （）
单项选择题 As an alternative to the conventional seawater cooling system, is based on principles about cooler locations, （）flow control and preheating, but with a central cooler and one additional set of pumps（）.
单项选择题 （）is harmful for fuel pumps, fuel valves, cylinder liner, exhaust valve seats, and the turbocharger blades as well.