It takes strong character to find happiness in the face of adversity, but scientists often have found that aspect too vague a topic to study.

在逆境中寻找幸福需要坚强的性格，但科学家常常发现，这个方面太含糊了难以对其进行研究。

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Both words are normally used in so vague a way that any definition is liable to be challenged, but one must draw a distinction between them, since two different and even opposing ideas are involved.

通常这两个词使用起来都表意不清，以至于任何对这两个词的定义都受到质疑。但是，我们必须要分清两者，因为这关系到两种不同的、甚至是截然相反的思想。

youdao

Both words are normally used in so vague a way that any definition is liable to be challenged, but one must draw a distinction between them, since two different and even opposing ideas are involved.

通常这两个词使用起来都表意不清，以至于任何对这两个词的定义都受到质疑。但是，我们必须要分清两者，因为这关系到两种不同的、甚至是截然相反的思想。

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