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 materials
- Bthat it cannot be used in a dead ship situation with no electrical power to the CO2 pump
- Cthat it breaks down under extreme heat to form poisonous gases
- Dthere is no effect on a class A fire even in an enclosed space