It might be a natural feature formation, or possibly a sunken, round man-made object. UFO Battles Captured on Video?

这种形状可能是由一种自然特征所形成，或者也可能是一个沉没在海底的圆形人造物体。

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Formation of heterocyclic amines is a unique feature of animals including fish and bird meat such as chickens and eggs.

形成杂环胺是动物食品的特征，包括鱼、禽肉如鸡肉，还有蛋类等。

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The reason for the formation of this feature: first, it is related with his objective of creation.

这一特征形成的原因：首先，与词人的创作目的相关。

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One unpredictable feature of Parinacota is the snow formation known as penitentes, thin, icy spires that can grow several metres tall and can make progress difficult, or even impossible by blocking the usual climbing routes.

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Large air shows like those feature pilots pulling seemingly death-defying maneuvers in all manner of aircraft from biplanes to jets, precision formation flying, skydivers jumping from planes and, of course, screeching military jets pulling high-G maneuvers.

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