单项选择题
For an OSV not on an international voyage，an approved substitute for an impulse projected type line throwing appliance is a（）.
A.spring-loaded line thrower B.hand thrown buoyant line C.shoulder type line throwing gun D.heaving line
单项选择题 （）of the following conditions will cause a vessel’s bottom to be subjected to tension stresses.
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（）.
