单项选择题
（）may be a warning for an approaching storm.
A.The persence of cirrus clouds B.The low-hanging stratus clouds C.The altocumulus clouds D.The massive cumulus clouds
单项选择题 Nimbus means（）.
单项选择题 Alto stands for（）.
单项选择题 （）is an indication that the weather is about to clear.
