单项选择题
A.the ship has been named
B.the ship has been built
C.the ship has been signed
D.the ship has been registered
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?（）
单项选择题 Official proof of an American vessel’s nationality is contained in the（）.
单项选择题 Inspection of a Halon extinguisher involves checking the hose，handle，nozzle，and（）.