单选题There are two disadvantages to CO2 pump as a firefighting agent. One of these is the limited quantity available，and the other is（）.Athe lack of cooling effect on heated materialsBthat it cannot be used in a dead ship situation with no electrical power to the CO2 pumpCthat it breaks down under extreme heat to form poisonous gasesDthere is no effect on a class A fire even in an enclosed space
单选题
There are two disadvantages to CO2 pump as a firefighting agent. One of these is the limited quantity available，and the other is（）.
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
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