When two Olympic pools at Rio turned from azure blue to bright green earlier this week, people around the world were left scratching their heads.
원문출처 : http://www.cnn.com/2016/08/12/sport/why-are-swimming-pools-blue/index.html
원문출처 : http://www.cnn.com/2016/08/12/sport/why-are-swimming-pools-blue/index.html