Volunteer Li Yaqian is in charge of lockers 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. (Photo: Xinhua/Li Ziheng)

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. (Photo: Xinhua/Guo Xulei)

Volunteer Cao Ya'nan works 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. (Photo: Xinhua/Li Ziheng)

Volunteers provide help to a guest 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. (Photo: Xinhua/Li Ziheng)

A staff member (1st L) from Uzbekistan registers with the help of volunteers at the registration center for the 18th meeting of the Council of Heads of State of the Shanghai Cooperation Organization (SCO) in Qingdao, east China's Shandong Province, June 4, 2018. (Photo: Xinhua/Wang Nan)

Volunteers greet guests at the registration center for the 18th meeting of the Council of Heads of State of the Shanghai Cooperation Organization (SCO) in Qingdao, east China's Shandong Province, June 4, 2018. (Photo: Xinhua/Jiang Kehong)

A staff member (1st L, front) from Uzbekistan registers with the help of volunteers at the registration center for the 18th meeting of the Council of Heads of State of the Shanghai Cooperation Organization (SCO) in Qingdao, east China's Shandong Province, June 4, 2018. (Photo: Xinhua/Jiang Kehong)