单项选择题
Corrosive liquids and acids should have which kind of label?（）
A.Skull and crossbones B.Yellow and white C.Red and white D.White and black
单项选择题 Conventional anchors are least likely to hold in a bottom consisting of（）.
单项选择题 Control of fire should be addressed（）.
单项选择题 Considering the general circulation of the atmosphere，the wind system between latitudes 30°N and 60°N is commonly called the（）.
