A woman says goodbye to her child at the railway station in Hangzhou, East China's Zhejiang province, Aug 21, 2012. As summer vacation winds down, children of migrants are going back to school in their hometowns, leaving parents to work in the city. There are nearly 20 million migrant laborers in Zhejiang, one of China's largest regions for migrant workers. [Photo/Xinhua]

A boy kisses his mother goodbye at the railway station in Hangzhou, East China's Zhejiang province, Aug 21, 2012. [Photo/Xinhua]