Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）

Flame failure in an automatically fired auxiliary boiler can from a/an （）

Using a file without a handle may result in （）

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

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

During the diesel engine running, the water level of F.W expansion tank should normally kept in the （） level of glass tube.

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

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

The cetane rating of diesel fuel is an indication of the （）

Thermostatic steam pressure reducing valves are used in the fuel oil service system to control the（）