找考题网-背景图
单项选择题

A.as a mass of warm,humid air rises into the atmosphere……

Clouds form().

A.as a mass of warm,humid air rises into the atmosphere and cools,condensing moisture into small droplets
B.as winds blow across bodies of water,the sun causes the moisture to be absorbed and move upward forming clouds
C.dry air compresses moisture from the atmosphere into clouds
D.when the relative humidity of the atmosphere is low