但是，在所有食肉动物中，下犬牙位于颌的前面，只有当嘴张大时上犬牙才能暴露出来。

But in all carnivores, the lower canines are in the front of jaws, and only if the mouth is wide open are the upper canines exposed.

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他偶然发现了一个450万年前的有袋动物的颌骨。

He came across the jawbone of a 4.5 million-year-old marsupial.

《柯林斯英汉双解大词典》

将黄颌蛇与其他被我们归类为毒蛇的蛇区别开来的，并不是它们没有毒液，而是缺乏一种将毒液输送到猎物体内的有效方法。

What separates colubrids from other snakes we have been classifying as venomous, is not the lack of venom, but the lack of an effective way to deliver the venom into its prey.

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