Cha`o ca'c ba'c, Ca'c ba'c co' nho+' ca'i dde^? xem ddo^. pha(?ng (spirit level) tie^'ng Vie^.t go.i la` gi` kho^ng? No' co' ca'i bong bo'ng o+? giu+~a a^'y. Co' le~ pha?i kie^'m quye^?n va^.t ly' lo+'p 5 dde^? tra cuu ma^'t. Ca'm o+n ca'c ba'c, Tha`nh