Kev raug mob ntawm cov neeg ua haujlwm: nres ua haujlwm tam sim ntawd, muab kev pabcuam thaum muaj xwm txheej ceev, thiab ceeb toom rau tus neeg saib xyuas.
Roj los yog to: tam sim ntawd tso tseg cov pa tawm, tshem tawm cov asphalt, thiab ntxuav nrog cov khoom siv roj tsim nyog.
Hluav taws kub: tam sim ntawd tua lub hwj chim hloov ntawm asphalt cua sov cov cuab yeej thiab siv ib tug tua hluav taws los tua nws. Yog tias qhov hluav taws kub tswj tsis tau, khiav tawm tam sim ntawd thiab hu rau lub chaw tua hluav taws.
Cov cuab yeej tsis ua haujlwm: tua lub hwj chim hloov, sim daws teeb meem, thiab yog tias qhov teeb meem daws tsis tau, ceeb toom rau lub tuam tsev tam sim ntawd.
