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

The shipboard oil pollution emergency plan will be invalid after （）

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

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

As soon as a diesel engine has started, which of the listed engine operating parameters should be checked FIRST?（）

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

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

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

The flash point of a residual fuel oil should be used to determine the highest temperature to which oil may be heated（）

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