Critics say there may be unknown risks.

评论家称，可能存在未知的风险。

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The researchers think there may be unknown compounds in coffee that protect against the disease.

研究人员认为，咖啡中可能有不明物质抵御疾病。

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The researchers think there may be unknown compounds in coffee that protect against the disease.

研究人员认为，咖啡中可能有不明物质抵御疾病。

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