12．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 other 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 1871to 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（傷害）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．
29 Dolphins are different from many other animals in that theyB．
A．live in groups
B．have large brains
C．are warmblooded
D．have their own language
30 Why did the sailors off the coast of New Zealand look for Jack？D
A．He was lonely and liked to be with people．
B．They enjoyed playing with him．
C．He was seriously wounded．
D．They wanted his help．
31 By telling the story of Jack the writer wanted to show thatA．
A．dolphins are friendly and clever
B．people are cruel to animals
C．Jack is different from other dolphins
D．dolphins should be protected by law．
分析 本文介紹了海豚的情況，并舉例說明海豚是人類的朋友．
解答 29．B 細節理解題．由第一段第五句Their brain is nearly the same size as our own，可知海豚與其他動物最大的不同就是他們的腦子和人類的腦子幾乎一樣大，故選B．
30．D 細節理解題．由第三段Jack met every boat in the area and showed it the way．可知海員們尋找Jack的原因是Jack為這些航船在危險航段指明方向，故選D．
31．A 寫作意圖題．全文都在講海豚的聰明與友好，所以正確答案是A；其他三個選項不能涵蓋全文，只是文章的一個細節．
點評 以細節題的考查為主，要求考生準確閱讀文章，在確定考查內容所在文章位置的時候，要根據上下文的語義串聯來確定答案．
