单项选择题
Which fire fighting agent has the greatest capacity for absorbing heat?（）
A.water B.dry chemical C.foam D.CO2
单项选择题 Which types of portable extinguisher should you watch for the reflash of the fire?（）
单项选择题 A portable foam fire extinguisher is placed in operation by（）
单项选择题 Before you begin administering artificial respiration, you should be sure the victim（）
