translation.en: If you're a human, you have about 400 different kinds of receptors, and the brain knows what you're smelling because of the combination of receptors and nerve cells that they trigger, sending messages up to the brain in a combinatorial fashion.
translation.zh: 人类有400种不同类型 的传感器， 并且大脑根据传感器 和刺激的神经的组合 知道你闻到了什么， 然后用一种组合的方式 将这个信息送达大脑。