홈 > Term: watchmen
watchmen
Weak coal pillars left in workings to give warning of an impending collapse.
- 품사: noun
- 분야/도메인: 광업
- 카테고리: 일반 광산; Mineral mining
- Government Agency: USBM
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작성자
- ed.young
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(V.I.P) 21084 포인트 - 100% positive feedback
(Milwaukee, United States)
