问题：
[单选] The purpose of the delivery check valve used in a diesel fuel injection jerk pump is to （）.
assist in a quick cutoff of fuel injection。allow oil backflow from the injector to the helix。reduce fuel oil pressure between injection strokes。meter the quantity of fuel delivered。
问题：
[单选] Excessive alkalinity of the water in an auxiliary boiler can cause （）.
caustic embrittlement of the boiler metal。acidic corrosion of the boiler metal。hard scale deposits on the boiler tubes。etching of the heat exchange surface。
问题：
[单选] The procedures recommended for auxiliary boilers having high salinity include （）.
treating with oxygen scavengers。securing the boiler and giving it a blowing down。increasing the pH。reducing the phosphate level。
问题：
[单选] Which of the following conditions may need to be reduced when operating a large, low speed, main propulsion, diesel engine at low loads?（）
Injection pressures。Control air supply pressure。Cooling water flow through after-coolers。Lube oil temperature。
问题：
[单选] Improper maintenance of the fuel oil burners in an automatically fired auxiliary boiler, could result in （）
increased fuel consumption。increased feed water consumption。fuel pump failure。combustion control system failure。
问题：
[单选] Operating a diesel engine for prolonged periods, with a closed freshwater cooling system, at temperatures lower than the normal design temperature can cause （）.
the formation of sulfuric acid。a decrease in lube oil viscosity。a decrease in cooling water pH。a thermostat failure。
问题：
[单选] The principal difference between loop scavenging and crossflow scavenging, as used in single acting diesel engines, is the （）
direction of air flow within the cylinder。sequence of port opening。method of opening exhaust ports。volume of air admitted to the cylinder。
问题：
[单选] The PRIMARY function of a waste heat boiler is to （）
reduce engine exhaust noise。reduce engine back pressure。recover heat which otherwise would be lost。increase turbocharger efficiency。
问题：
[单选] Large, two-stroke/cycle, main propulsion, diesel engine cylinders can be successfully pressure charged during normal operation, by using the （）.
exhaust gas temperature system。exhaust load system。constant or pulse pressure system。constant volume system。
问题：
[单选] Fuel injection systems meter fuel, atomize fuel, and （）.
create turbulence in the combustion chamber。aid in completing cylinder scavenging。inject fuel at the proper time。minimize fuel penetration into the cylinder。
