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

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

One of the reasons that cause oil flowed from sludge outlet of a self-cleaning separator is（）

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.

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

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

By comparing the exhaust gas temperature of each cylinder, the operator can determine if the load is balanced throughout the engine. The device most commonly used is a（）

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

Thermostatic steam pressure reducing valves are used in the fuel oil service system to control the（）

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