单项选择题

Animals that are good sleepers ______.

A．need to have a good sleep after they have exhausted themselves by getting rid of hunting animals
B．need to have a good sleep after they get tired from hunting other animals
C．are all mammals
D．almost always have a safe resting place

<上一题目录下一题>

热门试题

单项选择题

The statement, Horses and cows, for example, rarely close their eyes aims to show that ______.

A．these animals rarely need any rest
B．they almost always keep alert to danger
C．they often stay awake
D．their eyes are rarely closed even when they are asleep

单项选择题

How can researchers in sleep laboratories tell that the animals they are observing are asleep or not

A．They see if the animals respond to light and sound.
B．They do this by observing changes in the animals' brain signals, breathing, heartbeat, and muscle activity.
C．They see if the animals' eyes are closed.
D．They can tell this by seeing if the animals lie down or not.