单项选择题
A.clearing weather B.that a warm front has passed C.probable thunderstorm activity D.an approaching hurricane or typhoon
Cumulonimbus clouds are formed by（）.A.vertical air move...
单项选择题Cumulonimbus clouds are formed by（）.
A.vertical air movements B.heavy rainstorms C.horizontal air movements D.any movement of moist air
Corrosive liquids and acids should have which kind of l...
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
Conventional anchors are least likely to hold in a bott...
单项选择题Conventional anchors are least likely to hold in a bottom consisting of（）.
A.soft clay B.hard mud C.very soft mud D.sand
