Aerial photo taken on April 30, 2019 shows the scenery at the Wuqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Photo taken on May 1, 2019 shows the flowers in Wuqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Zhao Yusi)

Aerial photo taken on April 26, 2019 shows the Xiqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Aerial photo taken on April 30, 2019 shows a car moving on a road at the Wuqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Aerial photo taken on May 3, 2019 shows the Dongli country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Aerial photo taken on April 30, 2019 shows the scenery at the Wuqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Photo taken on May 1, 2019 shows the canal at the Wuqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Zhao Yusi)

Aerial photo taken on April 26, 2019 shows the Xiqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Aerial photo taken on April 26, 2019 shows the Xiqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)

Aerial photo taken on April 26, 2019 shows the Xiqing country park in Tianjin, north China. A dozen countryside parks in Tianjin have been built and renovated in recent years and have begun to serve as both tourism destinations and natural oxygen bars for the people. (Xinhua/Yue Yuewei)