The velocity of the wind，its steady direction，and the amount of time it has blown determines a wind driven current’s（）.

单项选择题When crossing a front,isobars tend to（）.

A.change from smooth curves within the air mass to sharp bends at the front
B.change from sharp bends within the air mass to smooth curves at the front
C.pass smoothly across the front with no change
D.become closer together at the front and pass through in straight lines

单项选择题Details of coast radio stations and radar stations can be found in（）.

A.Admiralty Chart
B.Admiralty Light list
C.Admiralty List of Radio Signals
D.Admiralty Notices to Mariners

单项选择题A current perpendicular to a vessel’s track has the greatest effect on the vessel’s course made good（）.

A.at high vessel speeds
B.at low vessel speeds
C.in shallow water
D.in deep water

单项选择题When compared to air temperature,which factor is most useful in predicting fog?（）

A.Vapor pressure
B.Dew point
C.Barometric pressure
D.Absolute humidity

单项选择题Radiation fog is more commonly encountered in（）.

A.spring
B.later winter
C.autumn
D.end of summer