Those results are especially worrisome, flu experts say, because pigs are believed to be mixing vessels in which avian and human flu viruses can combine into new strains.

流感专家说，那些结果非常令人不安，因为猪被认为是一种混合载体，在那里禽流感和人类流感病毒可能会结合形成新的病毒株。

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That’s worrisome, especially in the United States, where dams are rapidly aging, according to some researchers.

研究人员称，这十分令人担忧，尤其是在美国，那里的大坝正迅速老龄化。

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That’s worrisome, especially in the United States, where dams are rapidly aging, according to some researchers.

研究人员称，这十分令人担忧，尤其是在美国，那里的大坝正迅速老龄化。

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