单项选择题
A.does not change
B.improves rapidly
C.improves only slightly
D.becomes poor
单项选择题 After the initial cleaning of flue gas in an inert gas system the gas is passed through what device for final cleaning?（）
单项选择题 After sending a message describing the symptoms of an ill crew member，you receive a message containing the code MRL. This means “（）”.
单项选择题 After reporting a casualty to a mobile offshore drilling unit，which record must be retained on board? （）