单项选择题
An orange flag showing a black circle and square is a（）.
A.Signal indicating a course change B.Distress signal C.Signal of asking to communicate with another vessel D.Signal indicating danger
单项选择题 An inflatable liferaft should be manually released from its cradle by（）.
单项选择题 An inflatable liferaft is hand-launched by（）.
单项选择题 After the boat is at the top of the davit heads，the davit arms begin moving up the tracks and are stopped by the（）.
