Nws yog cov txheej txheem ntawm kev tsim cov khoom siv thev naus laus zis, uas yog kev tshuaj xyuas rov qab thiab kev tshawb fawb ntawm cov khoom lag luam, yog li txiav thiab muab cov qauv tsim ntawm cov khoom lag luam, cov qauv tsim, cov yam ntxwv ua haujlwm thiab cov kev qhia tshwj xeeb los tsim cov haujlwm zoo sib xws, uas yog tsis raws nraim tib yam khoom.