A
Dolphins are not fish, but warmblooded animals． They live in groups, and speak to each other in their own language． In this way they are like other animals, such as bees and birds． But dolphins are very different from almost all land animals． Their brain is nearly the same size as our own, and they live a long time—at least twenty or thirty years．
Like some animals, dolphins use sound to help them find their way around． They also make these sounds to talk to each other and to help them find food． We now know they do not use their ears to receive these sounds, but the lower part of the mouth, called the jaw．
Strangely, dolphins seem to like man, and for thousands of years there have been stories about the dolphin and its friendship with people．
There is a story about sailors in the 19th century． In a dangerous part of the sea off the coast of New Zealand, they learnt to look for a dolphin called Jack． From 1871 to 1903 Jack met every boat in the area and showed it the way． Then in 1903 a passenger on a boat called The Penguin shot and wounded Jack． He recovered and for nine years more continued to guide all ships through the area—except for The Penguin．
Today, some people continue to kill dolphins, but many countries of the world now protect them and in these places it is against the law to kill them．
【解题导语】 本文介绍了海豚的情况，并举例说明了海豚是人类的朋友的事实。
1．By telling the story of Jack the writer wanted to show that ________．
A．people are cruel to animals
B．dolphins are friendly and clever
C．Jack is different from other dolphins
D．dolphins should be protected by law
B 解析：写作意图题。全文都在讲海豚的聪明与友好，所以选B项；其他三个选项不能涵盖全文，只是文章的一个细节。
2．Dolphins are different from many other animals in that they ________．
A．live in groups B．have their own language
C．are warmblooded D．have larger brains
D 解析：细节理解题。根据第一段的Their brain is nearly the same size as our own．．．可知，海豚与其他动物最大的不同是它们的脑子和人类的脑子几乎一样大。故选D项。
3．Which of the following does the dolphin use to help it find its way around?
A．Its mouth． B．Its ears．
C．Its nose． D．Its eyes．
A 解析：细节理解题。根据文中的Like some animals, dolphins use sound to help them find their way around．可知，海豚是通过声音来确定方向的。故选A项。
4．Why did the sailors off the coast of New Zealand look for Jack?
A．They wanted his help．
B．They enjoyed playing with him．
C．He was seriously wounded．
D．He was lonely and liked to be with people．
A 解析：细节理解题。根据第四段的From 1871 to 1903 Jack met every boat in the area and showed it the way．可知，海员们寻找Jack的原因是它为这些航船在危险航段指明方向。故选A项。
