In the starting system, the automatic valve is controlled by（）, and the cylinder start valves are controlled by（）

单项选择题A marine diesel engine is started by（）

A.supplying high pressure oil into a hydraulic motor
B.supplying high temperature air into the cylinder
C.supplying high pressure air into the cylinder
D.electrical igniting

单项选择题In modern installations, the main engine and the standby auxiliary engines（）

A.can be started at low temperature and are free from preheating
B.usually are preheated by steam before being started
C.are kept at a constant temperature and free from preheating
D.are kept at a low temperature to save energy

单项选择题In order to maintain a constant outlet water temperature of 80-85℃ from the engine, a three-way valve is installed（）

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 （）

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（）

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