（）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.

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

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

Under MARPOL Code the ship to which it applies has to carry （）

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

As soon as a diesel engine has started, which of the listed engine operating parameters should be checked FIRST?（）

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

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（）

Using a file without a handle may result in （）