Volunteers and robot "Hai Hai" welcome guests at the media center of the Shanghai Cooperation Organization (SCO) Qingdao Summit in Qingdao, east China's Shandong Province, June 3, 2018. The media center is scheduled to open on June 6. A total of 370 volunteers from four colleges in Qingdao have stuck to their posts after three-month training. (Xinhua/Guo Xulei)