Chinese Premier Li Keqiang, President of the Republic of Korea (ROK) Moon Jae-in and Japanese Prime Minister Shinzo Abe plant an osmanthus tree together during a commemorative activity marking the 20th anniversary of the trilateral cooperation at the Du Fu Thatched Cottage Museum in Chengdu, southwest China's Sichuan Province, Dec. 24, 2019. (Xinhua/Ding Haitao)