Visitors pose for a photo in front of hospital ship Peace Ark of the Chinese People's Liberation Army (PLA) Navy during a warship open day event in Qingdao, east China's Shandong Province, April 24, 2019. A warship open day event was held on Wednesday in Qingdao, as part the multinational naval events marking the 70th founding anniversary of PLA Navy. (Xinhua/Ma Jing)