Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）

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

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

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

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

The main purpose of port State control is not to（）

（）connectors hold best if a wire is accidentally pulled or a connection becomes loose.

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

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

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