单项选择题
For operations in pack ice，a vessel should（）.
A.be on an even keel B.be trimmed slightly by the head C.have a drag of not more than 60 - 90 centimeters D.be ballasted so the forefoot is near the surface
单项选择题 Before entering an ice area，the ship should be（）.
单项选择题 Any vessel shall，if the circumstances of the case admit，avoid（）in a narrow channel.
单项选择题 An alternating light（）.
