Combo photo taken on May 3, 2020 shows Cao Xiongbin checking the temperature of his colleague (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Cao, 25, from Jingdezhen of Jiangxi Province, has been working as a staff member on the COVID-19 control and prevention since early time this year. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)

Combo photo taken on May 3, 2020 shows technician Dang Kunyang checking the construction progress (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Dang, 24, from Fuping County of Shaanxi Province, has been working as a technician for nearly 2 years. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)

Combo photo taken on May 3, 2020 shows scaffolder Liu Yuankui installing scaffolds (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Liu, 23, from Weining County of Guizhou, has been working as a scaffolder for more than 2 years. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)

Combo photo taken on May 3, 2020 shows steel fixer Tu Zhifei bundling reinforcing bars (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Tu, 30, from Zunyi of Guizhou, has been working as a steel fixer for more than 8 years. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)

Combo photo taken on May 3, 2020 shows engineer Xiong Jingfei on work (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Xiong, 29, from Fengcheng of Jiangxi Province, has been working as an engineer for more than 7 years. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)

Combo photo taken on May 3, 2020 shows steel fixer Ma Qingsong bundling reinforcing bars (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Ma, 22, from Qijiang District of Chongqing, has been working as a steel fixer since early time this year. Many young workers have stuck to their positions during Labor Day holiday. (Photo: Xinhua)