That ratio may have been higher in the nineteenth century; it's gradually trending down, but it's a slow-moving thing.

在19世纪这个比率要高一些,然后逐渐下降,但这是个缓慢变化的过程

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He's doing what he can, but change will be slow.

他在做他所能做的一切，但是变化却很缓慢。

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