Listen To This Musician Playing Beethoven on a 50,000-Year-Old Bone Flute Made By Neanderthals
有些人认为它是最古老的乐器，而另一些人则将其视为hyenas刺穿的骨头。
6 Common Myths About Drill Bits Debunked
钻头在许多不同的行业中起着重要作用。由小腿和长笛组成，它们用于在工件和物体中钻孔。小腿部分连接到钻头的chuck。附加后，…阅读更多
