A Chinese stone roller is on display in the World War II Gallery of the National Museum of the U.S. Air Force in Dayton, Ohio, the United States, on July 24, 2019. During World War II, thousands of Chinese workers used hand-hewn stone rollers to construct airfields throughout China to support Allied offensive air operations and the airlift of vital supplies into China. The National Museum of the U.S. Air Force displays more than 360 aircrafts and thousands of historical items that bring history to life. In its World War II Gallery, many exhibits reveal a memorable part of China-U.S. cooperation when the two countries joined hands in fighting fascism and safeguarding world peace. (Xinhua/Zhang Fengguo)