1. Ntau yam qauv tuaj yeem ua raws li arbitrarily, nrog cov xim ci, siv los ua veneer rau ntau yam ntoo-raws li vaj huam sib luag thiab ntoo, nrog rau siab hardness, hnav tsis kam thiab zoo kub tsis kam.2. Cov tshuaj tiv thaiv kab mob yog dav dav, thiab nws tuaj yeem tiv thaiv kev puas tsuaj ntawm cov kua qaub, alkalis, roj, cawv thiab ...
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