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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it's clear that you want to add a vector that looks like that, because then you go from the start of this to the finish of that, you end up at the same point and you get this invisible 0 vector.

显然应该给它加上这样一个矢量,因为从这个矢量的起点指向那个矢量的终点,最终指向的是同一个点,你就得到这个不可见的零矢量

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