This is true as the above derivation for a and b of opposite parity is an if and only if statement.

这是正确的，因为上面对 a 和 b 的奇偶性的推导是一个当且仅当命题。

youdao

Amino acids are the building blocks of protein, so you might think that foods high in protein would increase levels of tryptophan, but the opposite is true.

氨基酸是蛋白质的基石，所以，你可能认为，蛋白质含量高的食物，可以提高色氨酸的含量，但其实，应该相反才是对的。

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The true opposite of depression is vitality - the ability to feel a full range of emotions, including happiness, joy, pride, but also including sadness and grief.

跟抑郁完全相反的是充满活力——能让人们情绪饱满——感受到快乐、愉悦、骄傲、当然也包括悲伤和忧郁。

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But of course, the opposite is true of exporters, who have an incentive to use the weaker, government-controlled CNY.

BBC: Mr Osborne and China's long road to a global currency

Voters appear to trust Labour a lot less in the town hall than at Westminster (the opposite is true of the Liberal Democrats).

ECONOMIST: The local elections (1)

One thing, however, is certain: If Paul Krugman says the planet is running out of resources, the opposite is true.

FORBES: Magazine Article