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

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

The ISPS Code consists of a mandatory section-Part A, which shows（）

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

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 （）

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

Engine parameters shall be corresponded to NOx Technical Files. This is required by （）

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 shipboard oil pollution emergency plan will be invalid after （）