The quadruplet sisters Zhu Wanbing, Zhu Wanqing, Zhu Wanyu and Zhu Wanjie, who are going to be the fifth grade pupils next September, do their homeworks at home in Nanjing, east China's Jiangsu Province, Aug. 6, 2009. The quardruplet sisters were naturally conceived and born on August 11, 1999 in Nanjing. [Xinhua]