People visit the 2nd World Congress on Internal Combustion Engines in Jinan, east China's Shandong Province, April 21, 2021. The 2nd World Congress on Internal Combustion Engines, themed on "Green, Efficient, Intelligent and Reliable", attracted top scientists, entrepreneurs, experts, scholars and other scientific and technical workers in the industry to discuss technology trends and technical difficulties, promoting technological progress and the development of the industry. (Xinhua/Guo Xulei)
