Photo taken on Oct. 24, 2019 shows police robots displayed at the 22nd China Beijing International High-Tech Expo in Beijing, capital of China. The four-day expo opened here Thursday, drawing more than 1,200 exhibitors. (Xinhua/Ren Chao)

Photo taken on Oct. 24, 2019 shows police robots displayed at the 22nd China Beijing International High-Tech Expo in Beijing, capital of China. The four-day expo opened here Thursday, drawing more than 1,200 exhibitors. (Xinhua/Ren Chao)