单项选择题
Cargo in hold No.2 is on（） .
A.water B.oil C.fire D.A+B
单项选择题 CO2 and Halon extinguishers are used for electrical fire, as well as （）fire.
单项选择题 Lifeboat launching is operated at intervals of （）months.
单项选择题 Fire drill is carried out once a （）.
