Cov kev lag luam twg yog siv cov khawm tapered feem ntau?

Tapered nyees khawm tau pom feem ntau hauv kev lag luam chaw txua txiag zeb, tshwj xeeb tshaj yog me me - nplai quarries vim lawv txav tau. Cov teb xws li mining, infractures, tunnels siv nws.