题目

Cats are creatures of habit. They like to go to sleep about the same time every day and for a certain length of time. They seem to have a natural clock inside them that tells them when to sleep. Cats increase their regular sleep with occasional（偶尔的） cat naps（打盹）. Some experts feel that humans could also benefit from this habit. Cat naps help to build up energy in the body. They are also a good way to get rid of trouble! Since cats have the same moods（情绪）as humans, some experts believe that people can improve their moods. People might become happier.   A number汽车发动机的额定功率为80kw，它在平直公路上行驶的最大速度可达20m/s。那么汽车在以最大速度匀速行驶时所受的阻力是           N，如果汽车在行驶过程中所受阻力不变，当汽车以10m/s匀速行驶时的实际功率为        kw。