1. Qhov chaw pub mis yog kaw kom deb li deb tau, kom nws tsis yooj yim rau poob rau hauv cov khoom loj nrog cov cua ntws.
2. rotten ntim silicon carbide hmoov yuav tsum tsis txhob siv kom deb li deb li sai tau, tom qab rotten ntim tej zaum yuav tau tov nrog impurities, cuam tshuam rau tej nyhuv.