Four hundred drones make various formations in the sky during a rehearsal for the World Intelligence Conference in Tianjin, May 11, 2018. The conference will be held in the port city from May 16 to 18. (Photo: China News Service/Tong Yu)
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Four hundred drones make various formations in the sky during a rehearsal for the World Intelligence Conference in Tianjin, May 11, 2018. The conference will be held in the port city from May 16 to 18. (Photo: China News Service/Tong Yu)
