单项选择题
A.Maintains a constant head on the system
B.Reduces the likelihood of air or steam pockets formation
C.Provides a low pressure point for the addition of makeup cooling water
D.All of the above
单项选择题 To minimize corrosion, fuel oil strainer disks, spacers and scraper blades are made of （）.
单项选择题 The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and （）.
单项选择题 For a continuous operation diesel engine, a duplex filter unit would be the best arrangement because （）.