A white swan is seen on the Cuiping Lake in Jixian County of Tianjin, north China, Nov. 28, 2012. [Photo/Xinhua]

White swans are seen on the Cuiping Lake in Jixian County of Tianjin, north China, Nov. 28, 2012. [Photo/Xinhua]

White swans are seen on the Cuiping Lake in Jixian County of Tianjin, north China, Nov. 28, 2012. [Photo/Xinhua]

White swans are seen on the Cuiping Lake in Jixian County of Tianjin, north China, Nov. 28, 2012. [Photo/Xinhua]