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- 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. 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。
- His long boring story made me yawn. 他的冗长的故事听得我直打呵欠。
- It's just a dog's reflex movement. 这正是狗的反射运动。
- The meeting was one big yawn from start to finish. 那会议自始至终十分无聊。
- Sorry I hit you; it was a pure reflex. 对不起我撞著你了; 这完全是无意的。
- I gave a loud yawn, but he just kept on talking. 我大声打了个呵欠，可他还是不停地讲下去。
- He stretched himself with a yawn. 他打了个呵欠伸了伸懒腰。
- The play was a big yawn from start to finish. 那出戏从头至尾极其乏味。
- yawning reflex 呵欠反射
- Do you start the day with a yawn instead of a smile? 你每天是不是以一个哈欠开始工作，而不是满面笑容？
- Motor coordination; a motor reflex. 肌肉运动的协调; 肌肉运动反射
- An unfathomable chasm; a yawning gulf. 深渊，无底洞深不可测的裂缝; 张开的深壑
- A cavernous yawn; cavernous echoes. 瓮音的呵欠; 洞中的回声
- A law should be a reflex of the will of the people. 法律应该是全民意志的反映。
- He smothered a yawn behind his hand. 他用手挡住嘴遮掩自己打哈欠。
- It is very useful to use a miniature reflex camera. 使用小型反光镜照相机很有用。
- He stood yawning, his pyjama jacket gaping open. 他敞开睡衣站着打呵欠。
- Yawning is a sign that you are sleepy or tired. 打呵欠表示你困了或是累了。
- I have get a twin - lens reflex camera . 我有一架双镜头反射式照相机。
- I have got a single - lens reflex . 我有架单镜头反射式照相机。
