单项选择题
A helicopter making a round trip from a helideck with refueling capabilities to an unmanned platform will take 45 minutes each way. The helicopter should be carrying enough fuel to last（）.
A.45 minutes B.1 hour and 15 minutes C.1 hour and 30 minutes D.2 hours
单项选择题 A floating ship with an initial negative metacentric height（）.
单项选择题 A capsized small sail vessel is best righted when what part of the vessel is downwind?（）
单项选择题 A cable used by helicopters for lifting or lowering persons in a pick-up operation is a（）.
