单项选择题
One of the principal dangers inherent in liquefied petroleum gas is（）.
A.as it warms up it becomes heavier than air B.the way it reacts with sea water C.the strong odor it produces D.its low temperature causes frostbite or freezing
单项选择题 Inerting means（）.
单项选择题 In setting the valves on a steam-smothering system on a tank vessel，the master control valve to cargo tanks should be（）.
单项选择题 If you are fighting a fire below the main deck of your vessel，which action is most importantconcerning the stability of the vessel? （）
