But their Numbers have dwindled since the dawn of the 20th century, with unknown consequences for ocean ecosystems and the planet's carbon cycle.

但自20世纪初以来，它们的数量已逐渐减少，随之而来的是由此对海洋生态系统和全球碳循环产生的未知后果。

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He remained unknown to his professors, publishing instead the translations of François Villon, a rebellious 15th-century French poet, that launched his literary career.

取而代之的是，他热衷于发表弗朗索瓦-维庸（François Villon）的译作，这位15世纪法国的叛逆诗人开启了他的文学生涯之门。

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This mare of unknown ancestry was located in central Iowa during the early part of the twentieth century.

这种未知的祖先马奶位于爱荷华州中部，在二十世纪早期的一部分。

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The new ship will also have amenities unknown a century ago, like air conditioning.

WSJ: Billionaire launches plans for Titanic replica

For almost a century he was virtually unknown and only in the last two decades has he re-emerged.

ECONOMIST: English letters

No single development has altered the workings of American democracy in the last century so much as political consulting, an industry unknown before Campaigns, Inc.

NEWYORKER: The Lie Factory