单项选择题
Water can put out common fires, such as （）.
A.wood，paper B.textile C.A+B D.oil
单项选择题 For the duties （）in one emergency, one person may do more than one job and one job may be done by more than one person.
单项选择题 Seven short blasts continued for one minute means （）.
单项选择题 Several sand boxes need （）.
