Balloons provided military aerial observation sites in the 19th century and were used in the 20th century by scientists such as Auguste Piccard to gather high-altitude data. 19世纪时曾利用气球做军事空中观测站,20世纪时,科学家奥古斯特?皮卡德用气球收集高空资料。
With a wingspan of 8.5 feet and weight of 12.5 pounds, Puma is a lightweight, hand-launched UAV that provides aerial observation at line-of-sight ranges up to 10 kilometers. “美洲狮”翼展宽8.
The birds perched on the television aerial. 鸟停在电视天线上。
The picture is much clearer with the new aerial. 装上新天线后画面清晰多了。
He showed me some aerial photographs. 他给我看了一些空中拍摄的照片。
Having the back showing or in view of the observer. 背面的显露出背面的或背对观察者的