![Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)](http://www.ecns.cn/hd/2019/06/06/61a4bca567bb444089ec900343d0a6df.jpg)
Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)
![Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)](http://www.ecns.cn/hd/2019/06/06/334b78d3310145fb8275d6e92ad77311.jpg)
Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)
![Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)](http://www.ecns.cn/hd/2019/06/06/0493ee2f461841f898b6f49046942695.jpg)
Animals swim in a pool at a zoo in Berlin, Germany on June 5, 2019 as the highest temperature in the city reached 30 degrees Celsius. (Photo/VCG)