A. Raws li cov txheej txheem kev kho deg sib txawv ntawm U-shaped iav, muaj ntau hom iav embossed, xim iav, thiab lwm yam hauv kev tsim thiab xaiv, ntxiv rau cov iav embossed, kev xaiv ntawm lwm cov iav yuav tsum tau sau tseg.B. U-shaped iav yog ib yam khoom uas tsis yog combustible.Yog...
Nyeem ntxiv