Many people say dolphins are intelligent． They seem to be able to think， understand and learn things quickly． But are they as smart as humans， or are they more like cats and dogs？ Dolphins use their brains quite differently from the way humans do． But scientists say dolphins and humans are very similar in some ways． How？

Like humans， every dolphin has its own "name"． The name is a special whistle （哨声）． Each dolphin chooses a specific （特有的） whistle for itself， usually by its first birthday． Dolphins are like people in other ways， too． They "talk" to each other about a lot of things﹣such as their age， their feelings， and finding food． They also use a system of sounds and body language to communicate． Understanding dolphin conversation is not easy for humans． No one "speaks dolphin" yet， but some scientists are trying to learn．

Dolphins are also social animals． They live in groups called pods， and they often join othersfrom different pods to play games and have fun﹣﹣just like people． Scientists believe playing together is something only intelligent animals do．

Dolphins and humans are similar in another way： both species make plans for getting things they want． In the seas of southern Brazil， for example， dolphins use an intelligent plan to get food． When there are fish near a boat， dolphins signal （发信号） to the fishermen to put their nets in the water． Using this method， the men can catch a lot of fish． Why do dolphins help the men？ There is an advantage for them ：they get to eat some of the fish that escape （逃脱） from the net．

（1）What is a dolphin's "name"？ 　　

A．	It is a kind of game．
B．	It is a body sign．
C．	It is a dolphin's age．
D．	It is a specific sound．

（2）What does the underlined word " others" refer to？ 　　

A．	Other fishes．
B．	Other people．
C．	Other dolphins．
D．	Other games．

（3）What can we infer from the passage？ 　　

A．	Some scientists can understand dolphin's system of sounds．
B．	Dolphins probably help fishermen by using their body language．
C．	Humans join dolphins' groups to get things we want．
D．	Dolphins can talk to humans about their age and their feelings．

（4）What's the main idea of the passage？ 　　

A．	Dolphins can communicate with each other at birth．
B．	Dolphins are social animals because they play together．
C．	Dolphins are smart and are like humans in some ways．
D．	Dolphins help humans do many things like catching fish．