When there are small differences between the heights of two successive high tides or two successive low tides，the tides are called（）.

A.Add one hour to the times listed under the reference stations
B.Subtract one hour from the time differences listed for the subordinate stations
C.Apply no correction as the times in the reference stations are adjusted for daylight savings time
D.Add 15° to the standard meridian when calculating the time difference

A.freshets
B.floods
C.river flows
D.seismic events

A.speed of the current at a particular time
B.maximum speed of the current
C.direction from which the current flows
D.direction in which the current flows