（） is not installed on the main switchboar.

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

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

To shut down a diesel engine after it exceeds the set maximum speed，which type of device listed should be used?（）

Using a file without a handle may result in （）

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.

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

If two A.C.generators are to be operated in parallel, the load is distributed evenly by（）

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（）