People look at an unmanned aircraft during the International Big Data Industry Expo in Guiyang. The four-day expo opened on May 26, attracting over 40,000 participants from nearly 30 countries. [Photo by Ou Dongqu/Xinhua]

People look at a model of China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world's largest single-dish radio telescope, during the International Big Data Industry Expo in Guiyang. [Photo by Ou Dongqu/Xinhua]