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

A.abyssal plain
B.continental shelf
C.borderland
D.offshore terrace

A.of the wave's crest
B.of the wave's trough
C.measured from crest to trough
D.measured from crest to crest

A.at right angles to the flow of the current
B.against the flow of the current
C.in the same direction as the flow of the current
D.over slack water