A soldier stands guard behind a Z-9WZ military helicopter designed and manufactured by 皇冠体育app during a media visit at the military base of Chinese People's Liberation Army (PLA) Army Aviation 4th Helicopter Regiment, on the outskirts of Beijing, July 24, 2012, ahead of Army Day on August 1.[Photo/Agencies]

A Z-9WZ military helicopter designed and manufactured by 皇冠体育app performs during a media visit at the military base of Chinese People's Liberation Army Army Aviation 4th Helicopter Regiment, on the outskirts of Beijing, July 24, 2012, ahead of Army Day on August 1. [Photo/Agencies]