If the coolant temperature of a closed cooling water system for a diesel enginegradually increases, the trouble usually is( ).

A．a broken shaft on the freshwater pump

B．an excessive accumulation of scale in the heat exchanger

C．an incorrect thermostatic element operating range

D．lube oil in the cooling water

[单选题]In any diesel engine closed freshwater cooling system, the lowest pressure exists at the （）.A . jacket water outletB . cooling water pump outletC . heat exchanger outletD . expansion tank atmospheric vent

[单选题]The temperature now is 6 degrees（）zero centigrade.A . onB . lowC . lowerD . below

[单选题]关于闭合容量(Closed Capacity)与闭合气量(Closed Volume)，哪一项是错误的()A .CC和CV值相等B .正常年轻人CV大约是肺活量的10%C .随年龄增长，CV逐渐增加D .60岁以上或45岁病人仰卧位时，CV是肺总量的40%E .气道病病人的CC/肺总量的变化早于CV/肺总量的变化

[单选题]If an auxiliary diesel engine coolant temperature is higher than normal, but the thermostat is determined not to be defective, you would suspect a/anA．cavitation erosion in the water jacketsB．excess corrosion inhibitor in the coolantC．dirty jacket wa

[单选题]E．ach cylinder is closed at the top by a _____, made of a special heat-resistant steel.A．cylinder linerB．coupling flangeC．cylinder coverD．piston crown

[单选题]In the closed cooling system, the water （）.A . is made to circulate out of the systemB . is made to circulate within the systemC . is made circulate within the systemD . is made circulate out of the system

[单选题]Each cylinder is closed at the top by a （）, made of a special heat-resistant steel.A . cylinder linerB . coupling flangeC . cylinder coverD . piston crow

[主观题]Miss Harper closed her eyes and----------（假装）to be asleep.

[单选题]What is head tank in the closed cooling water system used for?A．for the release of air from the cooling waterB．providing expansion room for heated cooling waterC．a place for implementing water and water treatment agentD．all of the above

[单选题]In a closed diesel engine freshwater cooling system, the amount of coolant flowing through the heat exchanger is controlled by the （）.A . suction pressure regulatorB . thermostatic bypass valveC . sea water temperatureD . water level in the expansion