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

（）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（）

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 （）

Which one is NOT the ‘clear grounds’ for a more detailed inspection?（）

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

When does auxiliary burner of incinerator put into operation? （）Ⅰ. start incinerator when it is coldⅡ. the sludge for dealing with is littleⅢ. the sludge for dealing with is largeⅣ. the water and impurity in sludge are too muchⅤ. the temperature in incinerator is lowⅥ. dealing with little solid rubbish

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