Cov ntaub ntawv dab tsi yog siv los ua cov qauv qauv?

Kev tsim thiab ua cov qauv qauv tuaj yeem muab faib ua pawg hauv qab no raws li cov khoom siv:
 

(1) Plastic prototypes;
(2) Silicone prototypes;
(3) Hlau qauv;
(4) Av nplaum prototypes;