Tam sim no, peb lub tuam txhab muaj 8 tus neeg ua haujlwm (suav nrog 5 tus kws tshaj lij engineers), muaj peev xwm los tsim cov khoom tshiab, nws muaj nws qhov chaw ua haujlwm abrasive.Cov teeb meem kev lag luam ua ntej thiab tom qab muag tuaj yeem teb tau los ntawm cov engineers laus.