The wheel and axle is really a sort of lever. An example of such a machine is the device used in old-fashioned wells to hoist up the water bucket.是什么意思_The wheel and axle is really a sort of lever. An example of such a machine is the device used in old-fashioned wells to hoist up the water bucket.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句