单项选择题
A.may be substituted for 10 percent of the required life preservers
B.should be stowed adjacent to lifeboats and emergency stations
C.may be used by boat crews and line handlers during lifeboat drills
D.should be used when carrying out duties near a weather deck's edge
单项选择题 Cargo vessels being navigated，and fitted with emergency lighting and power systems，shall have their emergency systems tested at least once（）.
单项选择题 An aircraft has indicated that he wants you to change course and follow him. You cannot comply because of an emergency on board. Which signal should you make?（）
单项选择题 All self-propelled vessels on an international voyage must be equipped with how many Emergency Position Indicating Radio beacons (EPIRB)? （）