Visitors are seen on the Germany Day of Beijing International Horticultural Exhibition in Beijing, capital of China, on May 13, 2019. The expo welcomes Germany Day on Monday. With a theme of "seeding the future," Germany's Pavilion presents how green initiatives and projects helped restore the environment after pollution, with pictures and videos highlighting the historic changes to Essen city, the Emscher River and the buffer zone of the inner-German border. (Xinhua/Zhang Chenlin)

　　Visitors are seen on the Germany Day of Beijing International Horticultural Exhibition in Beijing, capital of China, on May 13, 2019. The expo welcomes Germany Day on Monday. With a theme of "seeding the future," Germany's Pavilion presents how green initiatives and projects helped restore the environment after pollution, with pictures and videos highlighting the historic changes to Essen city, the Emscher River and the buffer zone of the inner-German border. (Xinhua/Zhang Chenlin)

　　Visitors are seen on the Germany Day of Beijing International Horticultural Exhibition in Beijing, capital of China, on May 13, 2019. The expo welcomes Germany Day on Monday. With a theme of "seeding the future," Germany's Pavilion presents how green initiatives and projects helped restore the environment after pollution, with pictures and videos highlighting the historic changes to Essen city, the Emscher River and the buffer zone of the inner-German border. (Xinhua/Zhang Chenlin)

　　Visitors are seen on the Germany Day of Beijing International Horticultural Exhibition in Beijing, capital of China, on May 13, 2019. The expo welcomes Germany Day on Monday. With a theme of "seeding the future," Germany's Pavilion presents how green initiatives and projects helped restore the environment after pollution, with pictures and videos highlighting the historic changes to Essen city, the Emscher River and the buffer zone of the inner-German border. (Xinhua/Zhang Chenlin)

　　Visitors are seen on the Germany Day of Beijing International Horticultural Exhibition in Beijing, capital of China, on May 13, 2019. The expo welcomes Germany Day on Monday. With a theme of "seeding the future," Germany's Pavilion presents how green initiatives and projects helped restore the environment after pollution, with pictures and videos highlighting the historic changes to Essen city, the Emscher River and the buffer zone of the inner-German border. (Xinhua/Zhang Chenlin)