An exhibitor sells a mooncake via livestreaming at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 22, 2021. [Photo/Xinhua]

A robot writes Chinese calligraphy, at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 22, 2021. [Photo/Xinhua]

People learn about a real estate project at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 22, 2021. [Photo/Xinhua]

Electronic products are on display at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 21, 2021. [Photo/Xinhua]

A visitor takes a photo of a hydrogen-powered electric tractor at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 21, 2021. [Photo/Xinhua]

Optical quantum chips are on display at the 12th Expo Central China in Taiyuan, North China's Shanxi province, on May 21, 2021. [Photo/Xinhua]