The flood and ebb tides alternates with each other.

涨潮和落潮交替更迭。

《新英汉大辞典》

Their number and strength, their ebb and flood, their play and counter play and above all the laws of their nourishment remain quite unknown to us.

他们的数量以及力量，他们的起起落落，他们的游戏和相反的游戏，超越所有的，它们自己营养的定律，那对我们还是未知的。

youdao

And Mr Rush's grandfather-perhaps the most influential of all, for the flavour of this man of the sea runs throughout the book as certainly as the ebb and flood of the tides.

还有他的祖父——也许是所有人中影响他最深的一个人，因为他对这个属于海洋的男人的喜爱始终贯穿于全书，这一点就像潮水的涨退一样确信不疑。

youdao

As the tide rises, a flood-tidal current moves in one direction and as the tide falls, the ebb-tidal current moves in the opposite direction.

UNESCO: L O S S A R Y