Question

15．Blue whales are the largest animals ever known to have existed on the planet，and they can grow to a length of 100feet and weigh more than 330，000pounds．But recently researchers have found that these whales are on the move and they have migrated （moved） from California waters to areas off Canada and Alaska for the first time since commercial whaling ended in 1965．
The researchers identified 15blue whales that have appeared off the coast of British Columbia and the Gulf of Alaska since 1997．Four of these whales were recognized as ones that were once sighted off California shores，suggesting that the whales are returning to an old migration pattern between the coasts．
Before commercial whaling began in the early 1900s，blue whales were found widely throughout the North Pacific and California waters．But from the 1920s to the 1960s，whaling severely reduced the whale populations．Blue whales never recovered in the Northern Pacific，making sightings in this area rare．However，much larger groups of whales have been observed close to California since the 1970s．
The scientists had previously thought that the California population was separate from the population that had historically lived in North Pacific waters．But the current study shows that whales off the coast of British Columbia and the Gulf of Alaska are likely part of the California population．
To identify the blue whales，the researchers looked at photos of cetaceans taken in the North Pacific Ocean and compared them with a library of blue whale pictures taken along the West Coast of the United States and Southern Pacific．Up to now，the researchers are not quite sure why the whales are changing their migration patterns，but they suspect that the whales may be following their food moving farther north by the changes in ocean conditions．
28．According to the passage，blue whales areD．
A．following the fixed route of migration
B．dying out due to commercial whaling
C．rarely found in the Southern Pacific
D．moving from the south to the north
29．The whale population in the northern PacificC．
A．is different from the California population
B．has become the largest group since the 1970s
C．is probably part of the California population
D．has lived there since the 1960s．
30．The underlined word"cetaceans"in Paragraph 5probably meansA．
A．whales species B．land creatures
C．ocean conditionsD．migration patterns
31．What might make blue whales migrate according to the researchers？B
A．Commercial whaling．B．Food resources．
C．Weather conditions．D．Life reproduction．

Answer 1

分析 本文主要讲述了科学家们对蓝鲸的研究，蓝鲸作为我们所熟知的最大的动物，近日正在由南向北迁移，并且研究人员已经在哥伦布比海岸发现了蓝鲸的行踪．

解答 28．D细节理解题．根据第一段But recently researchers have found that these whales are on the move and they have migrated （moved） from California waters to areas off Canada and Alaska for the first time since commercial whaling ended in 1965．可知最近研究发现这些蓝鲸从加利福尼亚迁徙到加拿大和阿拉斯加，即由南向北迁移．故选D．
29．C细节理解题．根据第三段blue whales were found widely throughout the North Pacific and California waters．But from the 1920s to the 1960s，whaling severely reduced the whale populations．Blue whales never recovered in the Northern Pacific，making sightings in this area rare可知蓝鲸在北太平洋和加利福尼亚到处都是．但在二十世纪二十年代到六十年代，数量急剧减少，在北太平洋很好看到蓝鲸了．由此可知，北太平洋的鲸鱼很可能是加利福尼亚的一部分．故选C．
30．A词义辨析题．根据第五段To identify the blue whales，the researchers looked at photos of cetaceans taken in the North Pacific Ocean and compared them with a library of blue whale pictures taken along the West Coast of the United States and Southern Pacific．可知为了分析蓝鲸，研究者看了北太平洋的鲸的照片，与美国西海岸的鲸的图书馆的照片进行对比．由此可知，"cetaceans"的意思是"鲸鱼物种"．故选A．
31．B细节理解题．根据最后一段Up to now，the researchers are not quite sure why the whales are changing their migration patterns，but they suspect that the whales may be following their food moving farther north by the changes in ocean conditions．可知直到现在，研究者不确定为什么蓝鲸要改变他的迁徙方式．但他们怀疑蓝鲸可能是随着食物的变化而进行流动的．故选B．

点评 本文考察学生的理解推断能力以及细心程度，只要抓住文章的关键词，采用寻读的方法查找细节，就能找到正确答案．