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 cubs Bao Di and Bao Mei rest 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. 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. Giant panda Hao Hao gave birth to twin cubs Bao Di and Bao Mei in August 2019. (Xinhua/Zhang Cheng)

Visitors view giant panda Hao Hao and her twin 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. Giant panda Hao Hao gave birth to twin cubs Bao Di and Bao Mei in August 2019. (Xinhua/Zhang Cheng)

A zookeeper feeds a giant panda cub 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)