单项选择题
A.spring-loaded line thrower B.hand thrown buoyant line C.shoulder type line throwing gun D.heaving line
（）of the following conditions will cause a vessel’s bot...
单项选择题（）of the following conditions will cause a vessel’s bottom to be subjected to tension stresses.
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
（）of my ship’s propeller is very strong.A.The running r...
单项选择题（）of my ship’s propeller is very strong.
A.The running reflection B.The turning effect C.The moving speed D.The changing sensibility
A crack in the deck plating of a vessel may be temporar...
单项选择题A crack in the deck plating of a vessel may be temporarily prevented from increasing in length by（）.
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
