Yuav kom nkag siab seb nws puas tsim nyog thov, nws yog ib qho tseem ceeb kom muaj kev nkag siab yooj yim ntawm nws. Yooj yim muab tso, PPF yog cov thev naus laus zis thev naus laus zis, ib puag ncig tus phooj ywg xim tiv thaiv zaj duab xis, feem ntau pom hauv kev lag luam tsheb nthuav dav. Cov neeg tsis paub txog kev lag luam tsheb yuav tsis paub txog nws. Nws yog pob tshab, muaj zog heev, hnav- tiv taus, thiab tsis yooj yim daj lossis deteriorate. Nws yooj yim siv rau lub tsheb qhov chaw, cais cov xim ntawm cov huab cua sab nraud thiab tswj nws cov xim qub thiab luster. Tsis tas li ntawd, nws yog ua los ntawm TPU, ib puag ncig tus phooj ywg thiab muaj kuab paug- cov khoom siv dawb uas tsis muaj kev puas tsuaj rau ib puag ncig, xim, lossis tib neeg.
