单项选择题
The difference between the heights of low and high tide is the（）.
A.period B.range C.distance D.depth
单项选择题 The current rates（）excess of 2 kn may occur with prolonged strong winds.
单项选择题 The Brazil Current flows in which general direction? （）
单项选择题 The best time to work a boat into a slip is（）.
