单项选择题
A.fuel B.oxygen C.heat D.electricity
The vapors given off by heated fuel oil are heavier tha...
单项选择题The vapors given off by heated fuel oil are heavier than air and are（）.
A.odorless B.explosive C.nontoxic D.visible
If it becomes necessary to pump bilges while a vessel i...
单项选择题If it becomes necessary to pump bilges while a vessel is in port, which of the following procedures should be followed?（）
A.Pump only if the discharge is led to a shore tank or barge B.Pump only during the hours of darkness C.Pump only on the outgoing tide D.Pump only as much as is necessary
You are about to enter a compartment to investigate a s...
单项选择题You are about to enter a compartment to investigate a suspected smoldering fireIf youre not wearing a self-contained breathing apparatus, you should test the compartments atmosphere to determine if there is/are （）.
A.sufficient oxygen to sustain human life B.an explosive mixture in the compartment C.a toxic atmosphere in the compartment D.All of the above
