8 Cov Txheej Txheem Kev Luam Ntawv Cov Ntawv Luam Ntawv Nws tuaj yeem ua haujlwm ntawm cov khoom tiaj tus, cov khoom siv kheej kheej, cov khoom nkhaus, thiab txawm tias qhov chaw concave thiab convex.Piv txwv li, cov khaub ncaws, ntoo, thiab lwm yam tuaj yeem luam tawm, nrog kev hloov pauv zoo.A...
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