单项选择题
（）are used for anchor gear in marine work where the chains must withstand the corrosive effects of seawater.
A.Chains B.Wires C.Ropes D.Lines
单项选择题 （） are two vertical supports，usually steel，one each side of the centerline of the ship used to support booms.
单项选择题 What is the primary disadvantage of a permanent chain chaser system?（）
单项选择题 What is the main reason to slush a wire rope?（）
