单项选择题
A.Manual fire detection system
B.Automatic fire detection system
C.Smoke detection system
D.Watchman's supervisory system
单项选择题 Which extinguishing agent is the best for use on electrical fires?（）
单项选择题 Which extinguishing agent is recommended in the Chemical Data Guide for use on a carbon disulfide fire?（）
单项选择题 Which extinguishing agent is NOT recommended in the Chemical Data Guide for use on a cyclohexane fire?（）