The collision bulkhead shall be of（）.

The deck control valve to be（）after being repaired.

A.moved and fitting again
B.removed and refitted
C.reproduced and put on again
D.return and attached again

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The disinfection of various compartment in a vesel by filling them with a gaseous agents to destroy rats ect.means（）.

A.fire drills
B.washing and cleaning
C.fumigation
D.quarantine

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