单项选择题
Lifeboat launching is operated at intervals of three months.（）
A.救生艇下水每隔三周进行一次。 B.救生艇下水每三个月进行一次。 C.救生艇下水每三年进行一。 D.救生艇下水三个月。
单项选择题 CO2 extinguisher is for an electrical fire.（）
单项选择题 Apart from fire drill, there are also boat drill and emergency drill on board.（）
单项选择题 Crew members taking part in boat drills should muster, wearing warm outer clothing and life-jackets properly secured.（）
