Diesel engine air start system check valves are opened by （）

The condensers located in various stages of a flash evaporator are cooled by（）

（）are used to digest the sewage to produce innocuous sludge in a biological sewage treatment plant.

The Port State Control officer may witness a fire drill carried out by the crew assigned to these duties on the（）

The treatment of the fuel oils involves storage, heating, filtering and（）

Using a file without a handle may result in （）

For a given exhaust gas boiler, what is the quantity of its evaporation mainly determined?（）

If separating effect is not good, which measure should be taken （）

Which of the diesel engine components listed increase air density and helps to improve engine operating efficiency?（）

A purge recovery system is used in a centrifugal air conditioning or refrigeration system to （）