1. Dab tsi, yog dej khov qhuav? Cov dej khov qhuav yog cov tub yees uas muaj cov pa roj carbon dioxide (CO ₂), uas yog cov khoom dawb, zoo li cov daus thiab dej khov, thiab vaporizes ncaj qha yam tsis tau yaj thaum cua sov. Cov dej khov qhuav muaj qhov ua tau zoo tshaj ntawm cov tub yees, thiab tuaj yeem siv rau hauv kev tsim khoom ...
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