1. In the rooms, they watched television programs, or pictures of people yawning. 在屋里，他们看电视节目，或者人们打哈欠的相片。
2. Yawning is so contagious that chimpanzees can "catch" it from cartoons, according to research. 研究显示，打呵欠也会传染，黑猩猩能从卡通片里“学会”打呵欠。
3. When he pumped pure oxygen into subjects, for example, their frequency of yawning did not change. 当他将纯氧注入实验对象时，他们打哈欠的频率并没有发生什么变化。
英英解释
n.
1. an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom
2. gaping open as if threatening to engulf someone or something
3. with the mouth wide open indicating boredom or sleepiness
4. showing lack of attention or boredom
