单项选择题
A （）is used for lifting long heavy cargo.
A.derrick B.crane C.jumbo boom D.boom
单项选择题 （）cargo is unloaded by huge grabs on cranes or by large grain elevators.
单项选择题 At the discharging port, tankers pump the oil ashore using （）.
单项选择题 At the （）port, tankers pump the oil ashore using her own pumps.
