单项选择题
A.at the jacket cooler outlet to control the flux through the engine
B.at the jacket cooler outlet to control the flux through the cooler
C.at the engine outlet to control the flux through the engine
D.at the engine inlet to control the flux through the engine
单项选择题 About the jacket water, that of the auxiliary engines usually（） is circulated by pumps, and the main engine usually （）
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 （）