4周搞定2000+托福核心词
警戒，机敏
alertness
常考释义
According to conventional theory, yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing, through deeper breathing, the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom.
根据传统理论，当人们无聊或者困倦时就会打哈欠。伴随睡眠不足或无聊的是浅呼吸，而浅呼吸会降低血液中氧的含量。打哈欠可以通过深呼吸逆转这一点，增加血液中氧的含量从而达到提高警觉性的功能。
来源于：阅读OFFICIAL18 P2n. 警觉；警惕；留神；注意
The drug improved mental alertness.
这种药可以提高大脑的注意力。
以上图片仅供学习交流使用，版权归原作者所有，如有侵权，请与我方联系
