单项选择题
A.an engine-driven；as well
B.an engine-driven；has an independent pump
C.an independent；as well
D.an independent；has an engine-driven pump
单项选择题 The cooling system（） needs least maintenance work for in this kind of system（）
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（）.