单项选择题
A.Concentration of weight aft B.Concentration of weight forward C.Concentration of weight amidships D.Concentration of weight at both ends of the vessel
A.The running reflection B.The turning effect C.The moving speed D.The changing sensibility
A.cutting a square notch at each end of the crack B.drilling a hole at each end of the crack C.slot-welding the crack D.welding a doubler over the crack