1. What is the main purpose of the lecture?
A. To explain why people sleep at night rather than during the day
B. To discuss the problems caused by a lack of sleep
C. To explain why muscles in the body need sleep
D. To explore benefits that are provided by sleep but not by regular rest
2. Why does the professor mention that sleep is a risky behavior?
A. To suggest that resting while awake is better than sleeping
B. To indicate how important the benefits of sleep must be
C. To explain why many animals sleep during the day
D. To explain why birds sleep less than mammals
3. According to the professor, why is the sleep of dolphins unusual?
A. Their sleep is interrupted whenever they need to come up for air
B. They can move around while they are asleep
C. In every dolphin group only half of the dolphins are asleep at any given time
D. Their brains show no activity during sleep
4. What does the professor conclude about the view that the main function of sleep is to allow the body to recover from physical activity?
A. It is true for all animals except marine mammals
B. It’s supported by measurements of brain activity.
C. It explains why sleep has evolved
D. It is not convincing when examined more closely
5. According to the hypotheses discussed by the professor, what determines how alert we feel at a particular time of the day? Click on 2 answers
A. The supply of certain chemicals in our brain
B. The chemical composition of our diet
C. The 24-hour cycle of mental activity
D. The time of day when we usually wake up
6. Why do the students say this:
A. To show the professor that they have understood the theory
B. To support the professor’s point that people tend to be active at the same time
C. To point out a fact that seems to contradict the hypothesis the professor just discussed
D. To indicate that they would like to change their sleeping habits
答案：D B B D AC C