Twenty-four helicopters fly in the formation of the number "90" symbolizing the epic journey of the People's Liberation Army (PLA) in 90 years during a military parade at Zhurihe training base in north China's Inner Mongolia Autonomous Region, July 30, 2017. China on Sunday kicked off a grand military parade to mark the 90th founding anniversary of the PLA. (Xinhua/Zha Chunming)