单项选择题
A.male coupling at both ends
B.female coupling at both ends
C.female coupling at the nozzle end and a male coupling at the hydrant end
D.male coupling at the nozzle end and a female coupling at the hydrant end
单项选择题 A fire has broken out on the stern of your vessel. You should maneuver your vessel so the wind（）.
单项选择题 A definite advantage of using water as a fire extinguishing agent is its characteristic of（）.
单项选择题 A cutoff valve in the fire-main system of a ship may be closed to protect the portion of the system on an exposed deck from（）.