鳍状肢可能确实是水生生物的必要反应，海龟、鲸鱼和儒艮也有鳍状肢。

Flippers may indeed be a necessary response to aquatic life, turtles, whales, and dugongs also have them.

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它们向我们展示了进化过程中半成品的样貌，而完全进化的结果是鲸鱼和儒艮。

They show us what the intermediates might have been like, on the way to extreme cases such as whales and dugongs.

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然而，从某种程度上讲，海龟并没有像鲸鱼或儒艮一样完全回到水中生活，因为它们依旧在海滩上产卵。

However, they are, in one respect, less fully given back to the water than whales or dugongs, for turtles still lay their eggs on beaches.

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