单项选择题
The jumbo boom can lift heavy cargo, the gantry crane can hoist containers.（）
A.重吊杆吊重货和集装箱货。 B.龙门吊能起吊重件货，重吊杆能起吊集装箱。 C.重吊杆能起吊重件货，龙门吊能起吊集装箱。 D.龙门吊吊重货和集装箱货。
单项选择题 The SWL of the derricks are different from 5 tons to 10 tons.（）
单项选择题 Most general cargo ships have two derricks and two winches at each hatch.（）
单项选择题 We must use any stores carefully and return them after using.（）
