The nine-year-old Zhang Sichen (R) interacts with her three-month-old sister Zhang Yuchen in Qianshuiwan Community of Shushan District in Hefei, East China's Anhui province, July 27, 2016. To enrich summer vacation of left-behind children who came to cities for family reunion with their parents, some cities provided voluntary services and venues to organize a variety of activities for them.[Photo/Xinhua]