주시하고 있는 사람들

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  Betsey Keeton

  https://sciencealert.co.uk/%ec%98%a8%eb%9d%bc%ec%9d%b8-%eb%b0%94%ec%b9%b4%eb%9d%bc-%ec%95%88%ec%a0%84%ed%95%98%ea%b2%8c-%ec%a6%90%ea%b8%b0%eb%8a%94-%eb%b0%a9%eb%b2%95/