A contestant takes part in an unmanned aerial vehicle (UAV) obstable course race during a juvenile science festival in Yinchuan, northwest China's Ningxia Hui Autonomous Region, Sept. 21, 2019. (Xinhua/Feng Kaihua)

Choir members perform during a commemorative event held at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders on the occasion of the International Day of Peace in Nanjing, capital of east China's Jiangsu Province, Sept. 21, 2019. (Xinhua/Ji Chunpeng)

Syrians set free balloons during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo by Ammar Safarjalani/Xinhua)

People visit an exhibition on the art of Chinese characters in Changsha, capital of central China's Hunan Province, Sept. 21, 2019. The exhibition will last until Oct. 27. (Xinhua/Chen Zeguo)

Photo taken on Sept. 20, 2019 shows sheep grazing on a grassland in Ar Horqin Banner of north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)

A villager harvests water chestnuts in Feijiadai Village, Linghu Town of Huzhou, east China's Zhejiang Province, Sept. 21, 2019. (Xinhua/Huang Zongzhi)

A Palestinian protester uses a slingshot during clashes on the Gaza-Israel border, east of Gaza City, Sept. 20, 2019. (Photo by Mohammed Dahman/Xinhua)

British Labour Party leader Jeremy Corbyn listens as he attends the Labour Party Annual Conference 2019 in Brighton, Britain on Sept. 21, 2019. (Xinhua/Han Yan)

A policeman demonstrates abseiling skill during the Vienna Police Day celebration in Vienna, Austria, Sept. 21, 2019. A grand parade was held in Vienna on Saturday to celebrate the 150th anniversary of the Vienna Police. (Xinhua/Guo Chen)

Villager Dainzin Quzhen (front) holds a traditional rite in front of her new house in Lhozhag Town of Lhozhag County, Shannan City, southwest China's Tibet Autonomous Region, Sept. 21, 2019. A total of 88 villagers from 28 households moved to their new two-story dwellings to improve housing conditions. (Xinhua/Jigme Dorje)

Aerial photo taken on Sept. 20, 2019 shows vehicles running on bridges in Nanning, capital city of south China's Guangxi Zhuang Autonomous Region. The 16th China-ASEAN Expo and the China-ASEAN Business and Investment Summit kicked off in Nanning on Saturday. (Xinhua/Cao Yiming)

A staff member serves beer during the first day of the Oktoberfest 2019 in Munich, Germany, Sept. 21, 2019. The 186th Oktoberfest, one of the world's largest folk festivals, officially opened here on Saturday. It is expected that around 6 million visitors from all over the world will enjoy festival beer and culinary delicacies here from Sept. 21 to Oct. 6. (Xinhua/Lu Yang)