When Dr. Yasir Hamad heard that a patient's tongue had turned black, he decided he needed to see it for himself.
원문출처 : https://www.cnn.com/2018/09/05/health/black-hairy-tongue-study/index.html
원문출처 : https://www.cnn.com/2018/09/05/health/black-hairy-tongue-study/index.html