单项选择题
A.Operate the trigger valve
B.Weigh the extinguisher
C.Test with a pressure gauge
D.Read the date of last test
单项选择题 There is a fire in the crew’s quarters of your vessel. You should（）.
单项选择题 There is a fire aft aboard your vessel. To help fight the fire，you should（）.
单项选择题 There are two disadvantages to CO2 pump as a firefighting agent. One of these is the limited quantity available，and the other is（）.