leaching, the recovery of copper from the drainage water of mines,________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. C was a well-established methord of mineral extration D was a well-established methord of extracting mineral that was \ 恩 答案是C 仅仅是因为C简洁吗~~还有哦~~不是一般动词好于名词吗？？？？？？？？
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发表于 2011-3-16 18:40:25
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