单项选择题
A.perpendicular to the isobars in their warm sectors B.parallel to the isobars in their warm sectors C.parallel to the line of the cold front D.perpendicular to the line of the cold front
Cumulonimbus clouds can produce（）.A.dense fog and high ...
单项选择题Cumulonimbus clouds can produce（）.
A.dense fog and high humidity B.gusty winds，thunder，rain or hail，and lightning C.clear skies with the approach of a cold front D.a rapid drop in barometric pressure followed by darkness
Cumulonimbus clouds are most likely to accompany a(n)（）...
单项选择题Cumulonimbus clouds are most likely to accompany a(n)（）.
A.high pressure system B.cold front C.warm front D.occluded front
Clouds that form as small white flakes or scaly globula...
单项选择题Clouds that form as small white flakes or scaly globular masses covering either small or large portions of the sky are（）.
A.cirrus B.cirrostratus C.altostratus D.cirrocumulus
