And the exact contributions of man and nature to the changes taking place are surely unknown, even if it is accepted that man is making natural cycles more pronounced.

自然和人类对变化的确切影响，无疑是未知的，即使在公认人类对自然界循环的影响更加显著的情况下。

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But who's to say the trees they chew don't contain some unknown bacterium that stops sheep becoming man-eaters?

但谁又敢说它们咀嚼的树木中也会含有那种防止羊吃人的未知细菌呢？

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At Siemens, the 163-year-old industrial symbol of GermanyInc., it was long unknown for a man to take time off for children.

在有163年历史的德国工业象征——西门子公司，很长时间里没有听说有哪位男性为照看孩子而请假。

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And the strong man, still holding the small child, drifted away on the shadowy river that flows forever to the unknown sea.

VOA: special.2009.06.06

Brian Polite said Wednesday that a trooper interviewed her around 4:30 a.m. that morning at the Thomas Edison service plaza in Woodbridge and took a report that an unknown man had thrown her to the floor of the bus and then onto the road.

WSJ: Woman sues Eagles' McCoy, claiming assault on bus

"If this present government does not have the solution for us upcoming youth here, I'd rather the nation breaks, " said one young man playing football in Enugu near a statue referred to as "The Unknown Soldier" holding a gun aloft.

BBC: The Biafrans who still dream of leaving Nigeria

The unusual mummification of unknown man E, believed to be Pentawere, points to a "nonroyal burial" that includes use of goat skin to cover his body.

CNN: Study revisits mystery of Egyptian king's killing