Lub tais hom of elevator siv cov saw tsav los kho lub tais ntawm cov saw, kom cov khoom sib cais lossis hnyav tuaj yeem muab tso rau hauv ib lub thawv, uas tsis yooj yim rau sib tov.Cov khoom tuaj yeem ua kom sov lossis txias thaum thauj khoom rau ntim.