It was about in 1975/1974, when I was 6 or 7 years old. I lived in a plain(no mountain) in the north part of China. I can't remember the exactly day. It was at a summer noon. In that days, China is very poor, I seldom saw even a plane. After my grathermother death, I did nothing outside....Suddenly, (feeling let me)I looked straightly up. I found an cube matel, no lights, just over my head, an perfect cube about 1m. I think I can reach it if I jumped up. It seemed a same size of gear on the side of its bottom. Just when I looked at it, at the same time, it flyed away along the horizen, becoming a point in the far away, and disappearing, no any sound. The total process is about 1-3 seconds.