天文学家必须从黑洞对周围可见天体的引力影响推断出不可见的黑洞的存在。

Astronomers must infer the existence of black holes, which are invisible, from their gravitational influence on the visible bodies surrounding them.

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注意这些类中有些是不可见的。

Note that some of these classes are not visible.

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注意，两个排序列是不可见的。

Notice that the two sorting columns are not visible.

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In contrast, on the whole other side, you've got 3 things that are invisible, like the number 3.

相反地，另一方面,有些不可见的东西，例如数字。

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These invisible, vague things can never form the basis of a serious science.

这些不可见，定义模糊的东西,不能被划入严谨的科学范畴里。

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Things that are invisible never change.

不可见的东西永远不变。

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