A staff member operates robots for university teaching during the 12th China Beijing International High-Tech Expo in Beijing, capital of China, on May 20, 2009. The expo opened here Wednesday. [Xinhua]

Visitors look at a model of a solar power station which is planned to be built in Badaling Town, Yanqing County of Beijing, during the 12th China Beijing International High-Tech Expo in Beijing, capital of China, on May 20, 2009. [Xinhua]