Pedicle screws (3.5 mm diameter) were placed in the pilot holes. The spines were then dissected to separate the vertebrae, and the trajectory of the screws was visually inspected.

在引导孔内放置椎弓根螺钉(直径3.5 mm)，随即解剖并分离椎骨，此时就可以直观的观察到螺钉的轨线。

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In many projects, like the Simplon, for example, a small pilot tunnel is driven before the full diameter of the tunnel is excavated.

在许多隧道工程中，经如辛普龙大隧道，都要在隧道全面开挖前打一个导洞。

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Mine used small-diameter pilot drilling, then gradually reaming the borehole and finally completed to designed size.

宣东二号矿布设施工的大口径瓦斯抽放井以小口径导向钻进，后逐级扩孔成井。

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The drill would use that hole as a pilot and widen the diameter to about 28 inches, which officials have said is wide enough for the miners to be hoisted through.

CNN: Drilling to reach Chile miners yet to begin

The drill would use one of the three bore holes already made as a pilot and widen the diameter to about 28 inches, which officials have said is wide enough for the miners to be hoisted through.

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