1.High lub zog hlau khoom, dej nyab thiab plua plav, corrosed kuj.
2.Lower Yaus tawm tsam, PC yaug cov khoom siv, muaj kev nyab xeeb dua
· Cov khoom lag luam ntse ntse, ntse khau raj, cov hnab looj tes ntse, cov ntsiav tshuaj siv hluav taws xob, lub tsheb hluav taws xob, kev ntse lub khob dej. Txawb xov tooj ntawm tes. Them cov ntaub ntawv cable, thiab lwm yam kev lag luam