The mine once had a rich vein of silver, but it petered out.

这矿床原有很丰富的银矿，但已所剩无几了。

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But the campaign petered out before it reached most of Africa, where the problem is the worst.

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The road petered out in an area with little valleys, ridges, hills, and peaks, but it was not the contours of the land that created the uneven surface but, rather, the layers of things that had been thrown away: everything that the consumerist city had used up and expelled so that it could immediately enjoy the pleasure of handling new things had ended up in this unprepossessing neighborhood.

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