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

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

Using a file without a handle may result in （）

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

The shipboard oil pollution emergency plan will be invalid after （）

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

The flash point of a residual fuel oil should be used to determine the highest temperature to which oil may be heated（）

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

“Insufficiency of manning or insufficiency of certification of seafarers” is an identification of a（）

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