单项选择题
A.an unprotected drop-light bulb
B.careless disposal or storage of material
C.smoking in bed
D.worn electrical wires on power tools
单项选择题 Records of tests and inspections of a cargo vessel’s fire extinguishing systems shall be kept on board（）.
单项选择题 Port of Registry refers to the port where（）.
单项选择题 On vessels over 100 gross tons，whose responsibility is it to ensure that all able seamen in the vessel’s crew have the documents and qualifications required by law and regulation?（）