black

登录

单项选择题

Today’s discussion is about a common animal reaction--the yawning. The dictionary defines a yawn as "an involuntary reaction to fatigue or boredom". That’s definitely true for human yawns but not necessarily for animal yawns. The same action, the yawn, can have quite different meanings in different species.
For instance, some animals yawn to intimidate intruders on their territory. Fish and lizards are examples of this. Hippos use yawns when they want to resolve a quarrel. Observers have seen two hippos yawn at each other for as long as two hours before they stop quarreling.
As for social animals like baboons or lions--they yawn to set up the pecking order within social groups, and lions often yawn to calm social tensions. Sometimes these animals yawn for a strictly physiological reason-- that is to increase oxygen levels. And curiously enough, when they yawn for a physical reason like that, they do what men do--they try to stifle the yawn by looking away or by covering their mouths.

What’s the main topic of the monologue()

A.Different animals’ yawns.
B.Human’s yawn.
C.Fish’s yawn.
D.Social animals’ yawns.

相关考题

单项选择题 How many people applied but didn’t run the race()

单项选择题 Which of the following is covered in BCD International programs()

单项选择题 21().

All Rights Reserved 版权所有©PP题库网库(pptiku.com)

备案号:湘ICP备14005140号-5

经营许可证号:湘B2-20140064