然而，这些品牌企业似乎并未觉察到这点看来显而易见之处。
However, brands seem to have missed this seemingly self-evident point.
很长一段时间，人们都相信打哈欠是因为血液里二氧化碳太多而氧气不足，大脑茎干觉察到这点于是触动了打哈欠的神经。
It was long believed you yawned when there was too much carbon dioxide and not enough oxygen in your blood. A part of your brain called the brain stem detected this and triggered the yawn reflex.
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