For small rotary rock drill bits and rotary prospecting bits to cut soft, medium-hard rock.

用于中小规格冲击钻及旋转勘探钻具，凿进软岩层、中硬岩层。

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"Medium" on guitar and drums with the Beatles also seems easier than "medium" on "Rock Band, " while "hard" was sometimes just challenging enough for people who had played many times before, with "expert" mode still perhaps beyond reach.

CNN: Review: 'Beatles: Rock Band' fun for jamming in groups