单项选择题
What is the first visible indication of the presence of a tropical cyclone or hurricane（）.
A.Stratocumulus clouds or strange birds B.Rain and increasing winds C.An exceptionally long swell D.Dark clouds and the“bar”of the storm
单项选择题 Two well-developed high pressure areas may be separated by a（）.
单项选择题 Tropical cyclones are classified by form and intensity.Which system does not have closed isobars（）.
单项选择题 The wind is（）and decreasing.
