例如，四趾的始祖鸟先于三趾的始祖鸟出现，但北美的化石证据表明，这两种动物之间有一个急促而不均衡的转换过程。

The four-toed Eohippus preceded the three-toed Miohippus, for example, but North American fossil evidence suggests a jerky, uneven transition between the two.

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猪牛两种动物中，后者较有价值。

Of pigs and cows, the latter (=the cows) are more valuable.

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想象两个基因，两种动物各自含有自己的基因。

Imagine two genes, two sorts of animals each containing their own gene.

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It can come from animal sources and from vegetable sources, and the two have different impacts on health.

它可能来自动物,也可能来自植物,这两种对健康的影响各不相同

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Imagine two genes, two sorts of animals each containing their own gene.

想象两个基因，两种动物各自含有自己的基因。

耶鲁公开课 - 心理学导论课程节选