Tourists visit the Garden Expo Park in Beijing, capital of China, July 9, 2013. The 9th China (Beijing) International Garden Expo is held here from May 18 to Nov. 18, 2013. (Xinhua/Wang Xibao)

Students visit the Garden Expo Park in Beijing, capital of China, July 9, 2013. The 9th China (Beijing) International Garden Expo is held here from May 18 to Nov. 18, 2013. (Xinhua/Wang Xibao)

Students visit the Garden Expo Park in Beijing, capital of China, July 9, 2013. The 9th China (Beijing) International Garden Expo is held here from May 18 to Nov. 18, 2013. (Xinhua/Wang Xibao)

Students visit the Garden Expo Park in Beijing, capital of China, July 9, 2013. The 9th China (Beijing) International Garden Expo is held here from May 18 to Nov. 18, 2013. (Xinhua/Wang Xibao)