单项选择题
Cyclones that have warm sectors usually move（）.
A.westerly B.parallel to the isobars in the warm sector C.toward the nearest high pressure area D.faster than the accompanying cold front
单项选择题 Cumulus clouds that have undergone vertical development and have become cumulonimbus in form，indicate（）.
单项选择题 Cumulonimbus clouds are formed by（）.
单项选择题 A（）is created by a pressure gradient or slope in the water level.
