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
单项选择题 （）of my ship’s propeller is very strong.
单项选择题 A crack in the deck plating of a vessel may be temporarily prevented from increasing in length by（）.
