The changes are insidious, and will not produce a noticeable effect for 15 to 20 years.

变化是悄然发生的，15到20年间不会产生明显效果。

《柯林斯英汉双解大词典》

But would this effect really last for years?

但是这种影响真的将持续多年么？

youdao

The report also pointed out that while C. V. Raman won the Nobel Prize eighty years ago for the Raman Effect, most of the instruments available in India today using this principle are imported.

这份报告还指出，虽然拉曼博士八十年前就因发现“拉曼效应”获得了诺贝尔奖，然而时至今日，印度使用的、根据“拉曼效应”原理制造的工具器械，大部分都是进口的。

youdao

The scientists estimate this would have the same climate effect as taking all cars in the world off the road for ten years.

VOA: special.2009.06.19

Income inequality has been growing in the US for almost 40 years, with the effect that the core demand for goods and services is being eaten away.

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That hasn't been in effect for years, they say.

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