German Chancellor Angela Merkel (4th R, Front) and Mexican President Enrique Pena Nieto (3rd R, Front) visit the booth of Siemens 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)