running drill

• 活动钻,弓钻

running drill的用法和样例：

例句

1. With his bow drill, the workman bores small cavities for brads of soft copper to be hammered in, binding the pieces.
   他要用弓钻现在上面打几个小孔，然后软铜做成的曲头钉穿在里面好把碎片绑在一起。