Little or no change in the barometric reading over a twelve hour period indicates（）.

单项选择题In the relatively calm area near the hurricane center，the seas are（）.

A.moderate but easily navigated
B.calm
C.mountainous and confused
D.mountainous but fairly regular as far as direction is concerned

单项选择题In the doldrums you will NOT have（）.

A.high relative humidity
B.frequent showers and thunderstorms
C.steep pressure gradients
D.frequent calms

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（）.

A.high winds
B.high overcast clouds
C.calm or light winds
D.fog or steady rain

单项选择题In North America the majority of the weather systems move from（）.

A.north to south
B.south to north
C.east to west
D.west to east