单项选择题
A spanner is a （）.
A.cross connection line between two main fire lines B.special wrench for the couplings in a fire hose line C.tackle rigged to support a fire hose D.None of the above
单项选择题 A slow，gradual fall of the barometer indicates approaching（）.
单项选择题 A slow rise in the barometric pressure forecasts（）.
单项选择题 A sling psychrometer is used to measure（）.
