The deep well coal road cable of small diameter hole and high pre-tension structure and craft were studied according to the condition of high stress and composite roof in Fengcheng coal field.
结合丰城矿区高地应力、合顶板等复杂地质条件，研究深井条件下煤巷锚索采用小孔径、加高预应力的结构形式和施工工艺。
Last month the Washington University surgeons drilled a small burr hole, about the diameter of a pencil, into the patient's skull.
上个月华盛顿大学的外科医生用钻孔器在这个病人的头骨上钻了一个洞，直径大约和铅笔一样。
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