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At the instant when a string of casing being run from a ship is landed in the well head,（）.
A:the total weight in air of the casing string is removed from the ship
B:the hook load (weight of the casing string) is removed from the ship
C:the weight of the casing inside the riser is removed from the ship
D:the weight of the casing string added to the weight of the fill-up mud is removed from the ship

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出自：海船船员证

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