A helicopter performs at the 4th China International Helicopter Expo in Tianjin, north China, on Sept. 14, 2017. The expo which attacted 403 exhibitors from 22 countries and regions kicked off here on Thursday. (Xinhua/Bai Yu)
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A helicopter performs at the 4th China International Helicopter Expo in Tianjin, north China, on Sept. 14, 2017. The expo which attacted 403 exhibitors from 22 countries and regions kicked off here on Thursday. (Xinhua/Bai Yu)
