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题库 / Prep2008E2-SC-196
Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.
as a method of the extraction of minerals, it was well established
as a method of the extraction of minerals well established
was a well-established method of mineral extraction
was a well-established method of extracting mineral that was
had been a method of mineral extraction, well established
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D，that既可以修饰method也可以修饰mineral，意思上都说得通，引起指代歧义
E，过去完成时需要有过去的时间或动作做支撑，这里有did not；过去完成时表示一种状态时，通常表示以前时，而后来不再是的情况，这里没有说leaching现在不再是好的方法了，而是在说直到25前人们才发现leaching有效是因为细菌参与了这个过程。
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