Dab tsi yog prewash? Ntau tus neeg xav tias peb tab tom tham txog kev ntxhua khaub ncaws. Qhov tseeb tiag, qhov no yog qhov uas lawv tau ua nrog hnyav heev. Ua ntej, lawv tau soaked rau ob peb teev, ces wrung tawm thiab ntxuav. Tab sis cov kev ua haujlwm nyuaj no yog xav tau ntev npaum li tsis muaj lub tshuab ntxhua khaub ncaws tsis siv neeg