It senses it by chemical means and very importantly by mechanical means, because it has to move the food -- it has to mix all the various elements which we need for digestion.
它通过化学方式感受到食物， 更重要的是机械的方式， 因为它必须要移动这些食物， 它必须把我们消化吸收所需的所有不同元素 都搅和在一起。