单项选择题
A.conduct a fire drill
B.conduct a boat drill
C.log the fore and aft draft marks
D.test the emergency generator
单项选择题 Portable foam type fire extinguishers are most effective on（）.
单项选择题 Portable fire extinguishers must be provided for the cargo tank area of an unmanned tank barge（）.
单项选择题 Portable CO2 fire extinguishers should NOT be used to inert a space containing flammable liquids due to the danger of（）.