Left: File photo taken in 1977 by Zhu Li shows railway stewardess Di Jingru from Shijiazhuang railway crew section serving hot water for a passenger aboard a train. Right: Photo taken on Jan. 21, 2019 by Bao Liang shows a bullet train attendant gifting spring festival-themed posters to a passenger aboard the train D1867 from Chongqing in soutwest China to Guangzhou in south China.

Top: File photo taken in 1979 by Zhang Shenming shows staff members sorting books for children at Wuhan Children's Library in Wuhan, capital of central China's Hubei Province. Bottom: Photo taken on June 21, 2019 by Xiong Qi shows He Jing, a staff member of Hubei Provincial Library, inspecting the library in Wuhan. "When I started to work in the library, my colleagues had to label each book with a card, by which readers could find books they wanted.

Top: File photo taken in 1979 by Zhao Changchun shows Xia Xuncheng (R), a researcher with the Chinese Academy of Sciences, taking a sand sample in northwest China's Lop Nur Desert. Bottom: Photo taken on May 30, 2019 by Wang Peng shows Wang Bingyao (R) and Li Yunfei from the academic research of Shapotou station under Chinese ecosystem research network testing the surface temperature of sand dunes on the southern edge of the Tengger Desert in Zhongwei City, Ningxia Hui Autonomous Region.

Top: File photo taken in 1977 by Fan Mingtao shows Lu Lilian from Zhengzhou Railway Bureau patrolling the railway line at night. Bottom: Photo taken on Jan. 21, 2019 by Li An shows rail flaw detectors from the Zhengzhou section of China Railway Zhengzhou Group Co., Ltd. on the way for work. Instead of adopting simple methods like observing and striking rails with a hammer to detect rail flaws in the past, railway workers now carry out flaw detection with advanced equipment.

Top: File photo taken in 1974 and provided by Emperor Qinshihuang's Mausoleum Site Museum shows Yuan Zhongyi, the then-head of an archeological team, cleaning a terracotta warrior at the excavation site in Xi'an, capital of northwest China's Shaanxi Province. Bottom: Photo taken on July 4, 2019 by Li Yibo shows Lan Desheng, a cultural relic restorer at Emperor Qinshihuang's Mausoleum Site Museum, consolidating the color of a terracotta warrior after restoration in Xi'an.

Top: Photo taken in 1979 by Tang Yunli shows a tour guide from Shanghai Travel Agency briefing tourists about the Taihu Lake in Wuxi, east China's Jiangsu Province. Bottom: Photo taken on June 29, 2019 by Liu Ying shows Yan Ziqian from Shanghai Jin Jiang Travel serving Colombian tourists during a guided tour in Yuyuan Garden in east China's Shanghai. (Photos:Xinhua)

Left: File photo taken in 1975 shows doctors performing a gallbladder removal surgery (cholecystectomy) at a health center in Zhongshan, south China's Guangdong Province. Right: Photo taken on July 18, 2019 by Liu Dawei shows Chen Lingwu (L), director of the Department of Urology at the First Affiliated Hospital of Sun Yat-sen University, conducting an operation to repair the fallopian tube with the help of a robot-assisted laparoscope at the hospital in Guangzhou, capital of Guangdong.

Top: File photo taken in 1975 shows workers assembling televisions at a factory in Zhongshan, south China's Guangdong Province. Bottom: Photo taken on June 11, 2019 by Liu Dawei shows Zhang Qi (C), a senior electrical engineer in China's home appliance maker TCL Corp., checking robots' operating conditions at a production line of intelligent televisions in Huizhou, Guangdong Province.

Left: File photo taken in 1973 and provided by Li Renping (2nd L) shows Li learning Nixing pottery making techniques at a pottery factory in Qinzhou, south China's Guangxi Zhuang Autonomous Region. Right: Photo taken on June 14, 2019 by Zhang Ailin shows Li Renping (2nd L) studying the carving methods of Nixing pottery at a workshop in Qinzhou.

Top: File photo taken in 1978 shows workers making daily-use porcelain wares at a ceramic factory in Jingdezhen, east China's Jiangxi Province. Bottom: Photo taken on July 26, 2019 by Wan Xiang shows Huang Xu, a staff member of a ceramic 3D printing experience center, making porcelain vases via 3D printing facilities at Taoxichuan, a renovated production area in Jingdezhen of Jiangxi.