Ocean manganese nodules mining technology study is listed as special long term development item.

我国把大洋锰结核开采技术研究列为专项长远发展项目.

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But despite millions of dollars of investment, the commercial extraction of manganese nodules never became reality.

但是尽管拥有数百万美元的投资, 锰结核的商业化开采始终未能实现.

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