Feem ntau, cov dev me pib pom cov tsos mob ntawm cov hnub nyoog 9 txog 13 xyoos, cov dev nruab nrab ntawm 9 mus rau 11 xyoo, cov dev loj ntawm 7 mus rau 10 xyoo, thiab cov dev loj loj los ntawm 6 mus rau 9 xyoo. Lub sijhawm koj "tso" lawv cov tsos mob ntawm kev laus, qhov zoo dua lawv yuav txo tau lawv qhov tsis xis nyob.
