单项选择题 Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to（）

单项选择题 In a diesel engine cooling system, the high temperature alarm contact maker will be activated on excessively high water discharge temperature from the （）

单项选择题 In a diesel engine, a cylinder liner should be replaced if it is （） Ⅰ.Scuffed Ⅱ.Scored