Qhov tseem ceeb sib txawv ntawm cam khwb cia hlau thiab cam khwb cia hlau yog tias cov tshuaj muaj pes tsawg leeg sib txawv. Vim hais tias muaj pes tsawg leeg sib txawv, yog li lub koom haum cov khoom tsis zoo ib yam, feem ntau, cam khwb cia hlau yas thiab toughness yog zoo dua, manifested nyob rau hauv lub elongation, seem sh ...
Nyeem ntxiv