Without proof-- - you will see this if you ever take 803-- I will tell you that the speed of sound is the square root of Young's modulus divided by the density of the material.

现在不证明-,你们将在803章学到-,我告诉你们声速,是杨氏模量的平方根,除以介质的密度。

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QuietTM fire Door, made of high-quality material, is integrated with professional sound and fire proof design, and carefully manufactured and colored.

夸耶特tm隔音防火门融入了专业的隔音、防火设计、优质的材质、精细的制造、精美的着色等。

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