Once ivory has left its country of origin, and if it is seized by customs officials, it can be hard to identify its source and those responsible for acquiring it.

一旦象牙离开其原产国，并且如果象牙被海关官员抓获，那么就很难识别出其产地以及找出那些对此有需求的人。

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Yet little hard evidence has emerged about the seriousness of the attacks or their origin.

到目前为止，几乎没有证据表明这次攻击的严重性和它的起因。

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Lacking hard evidence, scholars of the past speculated broadly about the origin of language.

由于缺少可信的证据，对于语言的起源，以往的学者往往只能推测。

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It turns out that the origin of the phrase is hard to ascertain (note to Wiki), but it was popularized by a short lived tv series of the same name about innovative websites and online design that attempted to merge new and old media models.

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Given the ease with which proof-of-origin papers can be faked, it was hard to tell where any of it really came from.

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