Qhov twg yog qhov zoo dua qhuav lossis ntub cov cim?

Cov cwj mem ib nrab ntawm cov ntawv ntub dej ntub ua rau nws tsim nyog rau kev tsim cov cim ntev. Thaum cov cim qhuav qhuav yog qhov tsim nyog rau kev hloov pauv sai ntawm cov cim ib ntus.