单项选择题
A.shift in a clockwise manner
B.shift in a counterclockwise manner
C.continue blowing from the same direction
D.decrease in velocity
单项选择题 A tropical wave is usually preceded by（）.
单项选择题 A tropical wave is located 200 miles due west of your position，which is north of the equator. Where will the wave be in 24 hours? （）
单项选择题 A tropical storm is building strength some distance from your ship. Waves are coming from the east，with periods increasing from 5 seconds to 15 seconds. The swell is from the east. Where was the storm when these new swells were generated? （）