Pulley: in mechanics, a wheel that carries a flexible rope, cord, cable, chain, or Belt on its rim.
滑轮：力学上的一种装置，在边缘装有活动绳索、弦、缆、链条或带子的轮。
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The foetus can now grab and pull the long umbilical cord. The skeleton consists mainly of flexible cartridge. A network of blood vessels is visible through the thin skin.