单项选择题
Relative humidity is the percentage of water vapor that is in the air as compared to the maximum amount it can hold at（）.
A.a specific barometric pressure B.a specific temperature C.a specific wind speed D.any time
单项选择题 Recurvature of a hurricane’s track usually results in the forward speed（）.
单项选择题 Prevailing winds between 30°N and 60°N latitude are from the（）.
单项选择题 Plain language is usually used on marine weather（）.
