单项选择题 An inflatable liferaft is thrown into the water from a sinking vessel. What occurs automatically after the painter trips the CO2 bottles to inflate the raft?（）

单项选择题 You hear the general alarm and ship’s whistle sound for over 10 seconds. Traditionally，this is the signal for（）.

单项选择题 Is extra power available（）emergency while maneuvering?