Citizens attend a memorial ceremony for World War II air force heroes who died fighting against Japanese invaders in Nanjing, capital of east China's Jiangsu Province, April 4, 2014. A memorial ceremony was held Friday in Nanjing to honor air force heroes from China, the United States and the former Soviet Union who died in China while combating the Japanese invaders during World War II. The event took place just ahead of the Qingming Festival, which is observed by people to mourn for the deceased. (Xinhua/Han Yuqing)
