Still another system used in underground mining, which is called caving. This involves making the ore cave in on mined chambers or shafts. The ore is then removed by chutes that carry it down to a deeper level, where there is a haulage system.是什么意思_Still another system used in underground mining, which is called caving. This involves making the ore cave in on mined chambers or shafts. The ore is then removed by chutes that carry it down to a deeper level, where there is a haulage system.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句