The additional mark （）in the Classification Certificate for Machinery means propulsion apparatus is remotely controlled on the navigating bridge control station, and engine assembly control station is unmanned periodically.

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

To proceed to the assistance of a ship in distress is（）

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

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

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

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

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

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

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