Representatives of student volunteers respectively from five continents stamp their fingerprints at the Olympic Gymnasium Square of Beijing University of Technology in Beijing, capital of China, April 29, 2008. Student volunteers for the 2008 Beijing Olympic Games gathered on Tuesday to celebrate the 100-day countdown of the 2008 Beijing Olympic Games on April 29. The five representatives' fingerprints will be used on a memorial sculpture for student volunteers. (Xinhua Photo)

A martial art group performs on a square in Kaifeng, a city of central China's Henan Province, April 29, 2008. Different cities in Henan held public health-keeping activities to greet the 100-day countdown of the Beijing 2008 Olympic Games on Tuesday.(Xinhua Photo)