单项选择题
In the doldrums you can expect（）.
A.steady，constant winds B.frequent rain showers and thunderstorms C.steep pressure gradients D.low relative humidity
单项选择题 In reading a weather map，closely spaced pressure gradient lines would indicate（）.
单项选择题 In North America the majority of the weather systems move from（）.
单项选择题 In bad weather，what length of chain should be used with a single anchor? （）
