Hanover trade fair opens as Germany's Merkel advocates free trade

Visitors experience a physioball game at the booth of Sisyfox during the Hanover Fair 2018 in Hanover, Germany, on April 23, 2018. Hanover Fair, the world's leading industrial trade show, opened on Sunday, as German Chancellor Angela Merkel stressed the importance of free trade. (Xinhua/Shan Yuqi)