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.

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

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

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

Using a file without a handle may result in （）

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

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

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

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

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