The quadruplet sisters Zhu Wanbing, Zhu Wanqing, Zhu Wanyu and Zhu Wanjie are seen in a picture taken on September 1, 2002, walking hands in hands for their first kindergarden day in Nanjing, east China's Jiangsu Province. The quardruplet sisters were naturally conceived and born on August 11, 1999 in Nanjing. [Xinhua]