Cov npe sib txawv thiab cov qauv ntawm escalator kauj ruam chains muaj qhov sib txawv.
Thov nco ntsoov tiv tauj cov neeg siv khoom kom paub meej cov hom lossis cov khoom ua ntej kev yuav khoom; peb tuaj yeem muab kev qhia rau kev xaiv cov khoom.