“Humans have a code of ethics(行为规范),” says Marc Bekoff, an animal behavior expert at the University of Colorado．“If I don’t play in a certain way, you won’t play with me．Some animals have the same code”

　　Scientists recently discovered that animals which live in groups, such as elephants, foxes and wolves are especially likely to follow rules．If they don’t, and each does its own thing, the group might break apart．Group members would be forced to live alone．Then they’d have a harder time hunting and raising their young．

　　That’s probably why a traveling wolf pack stopped and waited to let its slowly moving leader catch up．Similar social ties may have caused a captive elephant to save her friend from drowning．Selfish reasons certainly motivated the male fox, who wanted to keep playing．

　　Sometimes, though, animals go out of their way to do what’s right, even when there’s nothing in it for them．Nobody knows why．“It might simply feel good to be kind, just as it does for humans,” says Bekoff．

　　If your friend wasn’t nice to you, what would you do? Maybe you would just walk away．That’s exactly what a wild red fox did when she was play-boxing with another fox．The larger fox, a male, began pushing too hard．The little female didn’t like fighting．She ran away quietly．

　　“He still wanted to play,” says Marc Bekoff．So the male fox ran after his playmate, bowed down, and rolled over．His body language meant, “Don’t leave．I’ll play nicely．” The female gave him another chance, and the male wrestled more gently this time．

1．How did the little female fox show her dissatisfaction with the larger male one?(no more than 5 words)

2．What’s the scientists’ recent discovery about the ethics in the world of animals?(no more than 15 words)

3．What does the sentence “It might simply feel good to be kind, just as it does for humans．” indicate?(no more than 13 words)

4．What’s the main idea of the passage?(no more than 11 words)