Giant panda Xiao Xin is seen at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019. (Photos: Xinhua)

Giant panda Heng Heng eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant pandas are seen at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Heng Heng eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Qiao Qiao eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Qiao Qiao eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Qiao Qiao is seen at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Qiao Qiao eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Heng Heng eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Heng Heng eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Heng Heng eats at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.

Giant panda Xiao Xin is seen at Qinling Research Base of Giant Panda Breeding of Shaanxi Academy of Forestry in Xi'an, northwest China's Shaanxi Province, Dec. 3, 2019.