Volunteers Lu Mengwu (1st R) and Tang Aiping (2nd R) take an oath during a ceremony for the International Horticultural Exhibition in Yanqing of Beijing, capital of China, March 29, 2019. A total of 20,000 volunteers will be recruited from 47 higher institutions, 60 companies and 16 districts to serve the whole event. (Xinhua/Ren Chao)