The "surface" of a black hole is the so-called event horizon, an imaginary surface surrounding the mass of the black hole.

黑洞“表面”就是所谓的活动视界，一个想像的黑洞质量周围的。

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The Earth's axis of rotation is tilted in relation to the ecliptic plane, an imaginary surface through Earth's orbit around the sun.

地球的自转轴与黄道面呈一定角度。黄道面是地球公转轨道所在的一个假想平面。

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