谢谢啦

LeannaChina

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
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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？？？？？？？？

LeannaChina

o ~一语惊醒梦中人啊~~！！谢谢啦 加油

geegee

that was 中的that可能指代mineral,不如c中的清楚。