Workers work at the construction site of Yanposhao grand bridge of Dunyun-Anshun expressway in Anshun, southwest China's Guizhou Province, April 8, 2020. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Workers work at the construction site of Yanposhao grand bridge of Dunyun-Anshun expressway in Anshun, southwest China's Guizhou Province, April 8, 2020. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Workers work at the construction site of Yanposhao grand bridge of Dunyun-Anshun expressway in Anshun, southwest China's Guizhou Province, April 8, 2020. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

A worker works at the construction site of Yanposhao grand bridge of Dunyun-Anshun expressway in Anshun, southwest China's Guizhou Province, April 8, 2020. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Workers work at the construction site of Yanposhao grand bridge of Dunyun-Anshun expressway in Anshun, southwest China's Guizhou Province, April 8, 2020. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)

Aerial photo taken on April 8, 2020 shows the Yanposhao grand bridge of Dunyun-Anshun expressway under construction in Anshun, southwest China's Guizhou Province. The construction of Dunyun-Anshun expressway project in Guizhou has fully resumed with strict measures to prevent the COVID-19 epidemic. (Xinhua/Liu Xu)