The designations A，B，C，D and E grades of cargo refer to the（）.

单项选择题The deck water seal of the inert gas system（）.

A.cools the inert gas and prevents soot from entering the cargo tanks
B.acts as an emergency shutdown when inlet pressures exceed the safe working pressure
C.prevents the backflow of hydrocarbon gasses into nonhazardous areas
D.relieves sudden large overpressures in the system

单项选择题The component in an inert gas system used for cleaning the gas of solid and sulphur combustion products，while simultaneously cooling the inert gas，is called the（）.

A.filter
B.cooler
C.scrubber
D.purifier

单项选择题The combined fan discharge rate in an inert gas system is related to the（）.

A.shoreside loading rate
B.maximum cargo pump discharge rate
C.boiler forced draft fan rate
D.size of the largest cargo tank

单项选择题The blowers of an inert gas generation system aboard a tanker，will be automatically secured if（）.

A.normal water supply at the water seal is lost
B.the temperature of the inert gas being delivered to the cargo tanks is more than 150°F
C.the cooling water supply to the scrubbers is lost
D.all of the above

单项选择题Spreading oil on the open sea has the effect of（）.

A.diminishing the height of the seas
B.lengthening the distance between successive crests
C.increasing the height of the seas
D.preventing the wave crests from breaking