Do you yawn? There are about 20 reasons that scientists think are possible for yawning after research. They do not know exactly why yawning happens, but they do know many facts about yawning.
你打哈欠吗？经过研究，科学家们认为打哈欠有大约 20 种可能的原因。他们还不清楚打哈欠的确切原因，但对打哈欠的许多事实都有所了解。
Everyone yawns in the same way, from babies to adults. First you open your mouth slowly, like a sleepy lion. Your mouth stays open for about five seconds. You take in a lot of air and then push it out. Then you quickly close your mouth. Yawning is contagious. If you see someone yawn, your body may reply by yawning too, much like a secret way of communication.
从婴儿到成人，每个人打哈欠的方式都是一样的。首先，你会慢慢张开嘴，就像一头困倦的狮子。你的嘴会保持张开状态大约五秒钟。你会吸入大量空气，然后再将其呼出。接着，你会迅速闭上嘴。打哈欠是会传染的。如果你看到别人打哈欠，你的身体也可能会以打哈欠的方式回应，就像是某种秘密的交流方式。
Many people say they yawn because they are tired. That might be true. People do often yawn before they sleep and after they wake up or before breakfast. However, people also yawn when they are excited or nervous. Yawning doesn't just mean you are lazy.
很多人说打哈欠是因为他们累了。这可能是真的。人们确实经常在睡觉前、睡醒后或早餐前打哈欠。然而，人们在兴奋或紧张时也会打哈欠。打哈欠并不只意味着你懒惰。
Yawning proves that your body needs to stay alert. When you yawn, you breathe deeply. You also stretch the muscles in your face, throat, neck and shoulders. Your eardrums stretch, too. Maybe this helps you to be quicker to notice things.
打哈欠表明你的身体需要保持警觉。当你打哈欠时，你会深呼吸。你还会拉伸面部、喉咙、颈部和肩部的肌肉。你的鼓膜也会得到拉伸。这或许有助于你更快察觉到周围的事物。
In some countries, people think yawning is not nice. People put their hands over their mouths to cover a yawn, and we often do the same thing when we cough. However, in other countries, people think yawning can let good things in.
在一些国家，人们认为打哈欠不太好。人们会用手捂住嘴来遮掩自己的哈欠，就像我们咳嗽时经常做的那样。而在另一些国家，人们则认为打哈欠可以带来好事。
Scientists do not spend much time studying yawning. That is probably because yawning does not hurt or cause any medical emergency. It is just a normal thing we do.
科学家们并没有花太多时间研究打哈欠。这很可能是因为打哈欠不会造成伤害，或引发任何医疗紧急情况。它只是我们的一种正常行为。