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凡是搞过土钻的人都知道,什么地层必须使用什么工具、什么钻头。但是,什么钻头适用于钻探稭料层(旧社会黄河大堤上堵口时所
Anyone who engages in earth drilling knows what tools and drill bits must be used for any formation. However, what drill bit is suitable for drilling the stratified layer (the old society when the Yellow River embankment blocking the time