单项选择题
A.The tank must be gas freed
B.The tank must be ballasted
C.The tank must be vented to the atmosphere
D.The bypass valve must also be closed
单项选择题 Using an inert gas system on a tanker has which advantage(s)? （）
单项选择题 Upon arrival at the discharging port，the inert gas system is（）.
单项选择题 Unless such oil tanker carries crude oil which is not suitable for crude oil washing，the oil tanker shall（）the system in accordance with the requirements of that Regulation.