相关考题
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单项选择题
Water may boil up around the stern of a vessel in a channel due to（）.
A.slack water when upbound
B.shallow water
C.a cross current
D.a head current -
单项选择题
Tropic tides are caused by the（）.
A.Moon being at its maximum declination
B.Moon crossing the equator
C.Sun and Moon both being near 0°declination
D.Moon being at perigee -
单项选择题
To make sure of getting the full advantage of a favorable current，you should reach an entrance or strait at what time in relation to the predicted time of the favorable current?（）
A.One hour after the predicted time
B.At the predicted time
C.30 minutes before flood，one hour after an ebb
D.30 minutes before the predicted time
