题目

It is known to us that every year of high school is a tough and busy time.【1】 We all know that not getting enough sleep is not good for our health, but it has been found that less sleep could even cause us to have fewer friends.According to researchers from the University of California, people who don’t get enough sleep are less willing to socialize with others.【2】The researchers carried out a small study. They tested 18 young participants who had just had a good night’s sleep, and tested them again after a sleepless night.【3】 When each person on the video got too “close”, 　　一只野兔发现老鹰在天空盘旋时，就立刻往自己洞穴的方向猛跑，这是动物的什么行为?为什么?