单项选择题
救生艇下水每隔三个月进行一次。（）
A. Lifeboat launching is operated at intervals of three months. B. Lifeboat launching is operated at intervals for three months. C. Fire drill is carried out once a month. D. Don’t operate two or more hatch covers at the same time.
单项选择题 Which letter means that oil-spilling has happened?（）
单项选择题 （）is best for electrical fire.
单项选择题 Which of the following is not the emergency equipment?（）
