简而言之，每个阿拉伯数字对应一个罗马数字，而且只有一个罗马数字映射到它。

In short, for each Arabic numeral, there is one, and only one, Roman numeral which maps to it.

youdao

这意味着在CSS中我们的一个类应该有一个原则而且只有一个理由去改变。

The principle implies that A class should have one, and only one, reason to change. In CSS we have.

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不管什么原因，当你被搁浅的时候，而且只有一个投资者，唯一的出路就是找到其他的投资者。

Whatever the reason, when you're stranded and you have one investor the only way out is to find new outside investors.

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For some others it might mean being basically restricted to the home, if not all the time, then the only exception being in public, in the company of a close-male relative as chaperon.

在一些别的地方可能意味着,基本上深居简出，即使不是一天到晚，也只有外出是例外，而且必须有一个男性近亲作监护人陪同。

普林斯顿公开课 - 人性课程节选