Sun Demin instructs his apprentice in making a sand bowl at Dongshanzhuang village of Qixia city, East China's Shandong province, July 31, 2017. Sun Demin is the seventeenth-generation successor of making Delu sand bowl, a kind of unique pottery used in Qixia city. He has learned to make Delu sand bowl since he was 16 years old. [Photo/Xinhua]