You are on a containership carrying a tank container that had been filled with sodium hydroxide solution. The container is empty but has not been cleaned. Which,if any,placard is required?().
A:No placard is required; the tank openings must be sealed
B:Empty placard with corrosive placard
C:Residue label with the UN number
D:Black and white corrosive placard
出自:海船船员证