单项选择题 If a CO2 fire extinguisher is not readily available, which of the listed fire extinguishers would be best suited to combat a small electrical fire in a switchboard?（）

单项选择题 You hear the general alarm bells and ships whistle sound for over 10 secondsTraditionally, this is the signal for （）.

单项选择题 The abandon ship signal sounded by the vessels whistle is （）.