Ib qho tseem ceeb ntawm peb cov yeeb nkab hlau uas zoo rau kev noj mov yog nws qhov yooj ywm heev. Cov yeeb nkab no tuaj yeem khoov thiab ntswj tau yooj yim kom haum rau hauv qhov chaw nqaim, ua rau nws siv tau rau txhua yam los ntawm kev nchuav cov kua ntses mus rau kev ntim cov thawv. Nws tsim kom sib dua ua rau nws yooj yim tuav, thaum nws cov qauv ruaj khov ua kom nws yuav tsis sib xyaw lossis tawg thaum muaj kev nyuaj siab. Cov yeeb nkab yooj yim ntxuav thiab saib xyuas. Kev ntxuav yooj yim heev; tsuas yog yaug nrog dej xab npum sov lossis muab tso rau hauv lub tshuab ntxuav tais diav.