If they knew how difficult it was to drill through the ard rock.

如果他们知道了钻透那坚硬的岩石有多么困难.

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If they knew how difficult it was to drill through hard rock, they would lose heart.

如果他们知道要钻透岩石层有多么难, 他们一定会绝望的.

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Used with our down - hole hammer, it can drill through complicated drilling holes are easy to collapse.

配合我厂生产的潜孔锤, 可以钻穿复杂,易坍塌底层.

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