Giant panda Hao Hao plays with her two cubs at the Pairi Daiza zoo in Brugelette, Belgium, Dec. 31, 2019. Giant panda Hao Hao gave birth to twin cubs Bao Di and Bao Mei in August 2019. (Xinhua/Zhang Cheng)

Giant panda Hao Hao plays with one of her cubs at the Pairi Daiza zoo in Brugelette, Belgium, Dec. 31, 2019. (Xinhua/Zhang Cheng)

Giant panda Hao Hao plays with one of her cubs at the Pairi Daiza zoo in Brugelette, Belgium, Dec. 31, 2019. (Xinhua/Zhang Cheng)

File photo taken on Nov. 14, 2019 shows zookeepers holding the panda twins Bao Di (L) and Bao Mei at the Pairi Daiza zoo in Brugelette, Belgium. (Xinhua/Zheng Huansong)

Giant panda cubs Bao Di and Bao Mei rest at the Pairi Daiza zoo in Brugelette, Belgium, Dec. 31, 2019.

A zookeeper holds the panda "Bao Di" at the Pairi Daiza zoo in Brugelette, Belgium, Nov. 14, 2019. ¦