yeej suav nrog cov txheej txheem hauv qab no: 1.Tabel txiav mechanism txiav tawm cov ntawv cim
2.Cov khoom xa tuaj rau lub tshuab nqus dej nqus
3. Cov nplaum lo nplaum yuav ncaj rau siv kua nplaum rau ob qhov kawg ntawm daim ntawv lo
thov koj xav tiv tauj peb yog tias koj xav tau cov ntsiab lus ntxiv