Above him an invisible plane droned through the night sky.

在他头顶上空一架隐形飞机飞过夜空，不断发出低沉单调的声音。

《柯林斯英汉双解大词典》

In an undated picture, a mock-up of the A-12 spy plane sits perched upside down on a testing pylon at Area 51-part of radar tests to reveal revealed how visible, or invisible, the design was to radar.

在一张未标明日期的图片中，一架实物模型的A - 12间谍飞机倒挂着停放在51区的一个测试塔上，这是为了测试该飞机的外观在雷达上可视或不可视的程度。

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He was burning with revenge and felt the need for a plane that would be pretty much invisible to Britain's Chain Home radar system.

他被复仇点燃了，他感到飞机的一项需求，即：充分有效地遁形于英国雷达监测网络系统。

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Thus, a spy plane could not be completely invisible if it were to be used for espionage or, indeed, flown at all, since its pilots would need to know its position relative to the ground.

ECONOMIST: How to weave a cloak that makes you invisible