Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

A keeper takes care of the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium, Sept. 9, 2019. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

Photo taken on Sept. 9, 2019 shows the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

A keeper takes care of the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium, Sept. 9, 2019. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)

A keeper takes care of the male cub of panda Hao Hao at Pairi Daiza zoo in Brugelette, Belgium, Sept. 9, 2019. An activity was held here to celebrate the one-month birthday of the twin panda cubs, which were born on Aug. 8. Both the male cub and the female cub are now in very good health condition, according to Pairi Daiza, a zoo in Brugelette in west Belgium's Hainaut province. (Photo: Xinhua)