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

Cold weather starting of a diesel engine may be made easier by（）

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

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

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

Which one is NOT the ‘clear grounds’ for a more detailed inspection?（）

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

When does auxiliary burner of incinerator put into operation? （）Ⅰ. start incinerator when it is coldⅡ. the sludge for dealing with is littleⅢ. the sludge for dealing with is largeⅣ. the water and impurity in sludge are too muchⅤ. the temperature in incinerator is lowⅥ. dealing with little solid rubbish

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

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