After the passage of a cold front the visibility（）.

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?（）

A.Scrubber
B.Demister
C.Deck water seal
D.Final filter

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 “（）”.

A.Apply ice-cold compress and renew every 4 hours
B.Commence artificial respiration immediately
C.Give enema
D.Pass catheter into bladder

单项选择题After reporting a casualty to a mobile offshore drilling unit，which record must be retained on board? （）

A.Record of drafts
B.Hull reports
C.Anchor record
D.Machinery repair book

单项选择题After putting on a self-contained breathing apparatus，you open the air supply and hear a continuous ringing of a bell. What does this mean? （）

A.The unit is working properly
B.The face mask is not sealed properly
C.The air bottle needs to be refilled
D.The air supply hose has a leak

单项选择题According to the Chemical Data Guide，epichlorohydrin is a(n)（）.

A.corrosive
B.class B poison
C.oxidizer
D.explosive