Tsis tas li ntawd xwb, tsis muaj ib yam dabtsi npaum li cas. Lawv nrhiav lub nrhiav nrhiav lub nrhiav nrhiav lub nroog. Yog li ntawd, peb yuav tsum ua li ntawd. Yog li ntawd, peb yuav pab tau tej teeb mechanics thiab pab tau tej teeb meebs teeb meeg, ces yuav pab tau tej pab kom lawv ua keeb