单项选择题
A.the lack of cooling effect on heated materials
B.that it cannot be used in a dead ship situation with no electrical power to the CO2 pump
C.that it breaks down under extreme heat to form poisonous gases
D.there is no effect on a class A fire even in an enclosed space
单项选择题 The wooden plug inserted in the vent of a damaged tank of a ship should be removed in case it is decided to（）.
单项选择题 The ventilation system of your ship has fire dampers restrained by fusible links. Which statement is TRUE?（）
单项选择题 The type of extinguisher which should be used for an electricity fire is（）.