Over the past few decades, the magnetic field has weakened rapidly enough to flip within a few thousand years, but this could also be part of a more limited variation.

在过去的几十年里，磁场极速减弱，导致逆转会在几千年内发生，但这也可能只是前奏的一小部分。

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Variation among humans is limited to the possible permutations of our genes.

人类的变化形式受限于我们基因可能的那些排列。

《柯林斯英汉双解大词典》

That does not mean using the same characteristics all over the page but the amount of variation should be limited.

这并不意味着在整个页面都使用相同的特征，而是应该进行有限的变化。

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National pay scales with limited regional variation mean that teachers and nurses are under-paid in London and the south-east, leading to severe labour shortages.

ECONOMIST: Labour and the unions