Giant panda "Shun Shun" plays at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua

Giant panda "Gong Gong" eats at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua

Giant panda "Shun Shun" enjoys sunshine at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua

Giant panda "Gong Gong" plays at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua

Giant panda "Gong Gong" eats at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua

Giant panda "Shun Shun" plays at the Hainan Tropical Wildlife Park and Botanical Garden in Haikou, south China's Hainan Province, Dec. 7, 2019. As the temperature drops, giant pandas "Gong Gong" and "Shun Shun" spend 6-7 hours outside their air-conditioned enclosures each day, according to the zoo. Photo:Xinhua