In some parts of the world there is often a slight fall in tide during the middle of the high water period. The effect is to create a longer period of stand at higher water. This special feature is called a(n)（）.

The height of a wave is the vertical distance（）.

Steam fog is most likely to occur on the Mississippi and Ohio Rivers in（）.

Radiation fog（）.

The apparent wind’s speed can be zero only when two conditions are present. One condition is that the true wind（）.

The drift and set of tidal，river，and ocean currents refer to the（）.

The apparent wind can be zero when the true wind is from（）.

The length of a wave is the length（）.

The place where a channel moves from along one bank of the river over to the other bank of the river is called a（）.

The horse latitudes are characterized by（）.