单项选择题
A tourniquet should be used to control bleeding ONLY（）.
A.with puncture wounds B.when all other means have failed C.when the victim is unconscious D.to prevent bleeding from minor wounds
单项选择题 A survival craft being used to pick up a person who has fallen overboard from a vessel should approach the person（）.
单项选择题 A snag or other underwater obstruction may form a（）.
单项选择题 A shipmate suffers a heart attack and stops breathing. You must（）.
