A teacher makes Sanyanxiao, a vertical end-blown flute with three sound holes, in Huadong Primary School in Agong Town of Zhijin County in Bijie City, southwest China's Guizhou Province, June 20, 2019. The Huadong Primary school has introduced this unique musical instrument of Miao ethnic group into class since 2016 to inherit the intangible cultural heritage. (Xinhua/Shang Yujie)