long-spiral drilling

• 长螺旋钻成孔

long-spiral drilling的用法和样例：

例句

1. While drilling big or deep holes, you should pull out drills regularly in order to take out scraps, do not intend to bore holes at once.
   当钻大的或深的孔时，要定时的退出钻头以带出碎屑，不要总是希望一次性的钻成。