Animal biologists in the U.S. state of Wyoming recently confirmed the death of the oldest-known grizzly bear in Yellowstone National Park. Grizzly is another name for the North American brown bear. This bear was 34 years old. Most male bears do not live that long. But he outlived the oldest-known female bears. He was known to park biologists as Grizzly 168. Grizzly 168 leaves an important legacy. He did his part to help the population of bears recover. In his lifetime, researchers estimate he fathered at least three groups of baby bears.
He was first captured and given a tattoo with his number in 1989. Officials made the decision to give the bear a lethal injection because of his poor health. The bear had lost a lot of weight and was killing young farm animals. Healthy male bears weigh about 200 kilograms. This bear only weighed 77 kilograms.
The U.S. Fish and Wildlife Service says healthy grizzly bears will sometimes chase and kill young animals for food. They also eat berries, roots, insects and fish. This old bear, however, was not able to eat much. He was so old that he had lost most of his teeth. Grizzly 168 was so old that it only had three remaining teeth. Recently, the bear would attack young cows. The bear would crush them with his jaws but would not leave any bite marks.
Officials said it was a hard decision to kill the bear because there are so few. Hundreds of years ago, there were lots of grizzly bears in North America. But as land was developed, many bears were killed. The Fish and Wildlife Service declared them threatened in 1975 when there were very few known bears in the United States. Most of them were in Alaska. Now they are protected and the population is increasing. There are still, however, only a little more than 1,000 grizzly bears in the U.S. outside of Alaska.
1.How did the oldest-known grizzly bear die?
A It died of hunger.
B It died of a disease.
C It died from human factors.
D It died from a traffic accident.
解析：选C。细节理解题。根据第二段第二句Officials made the decision to give the bear a lethal injection because of his poor health.可知，由于熊的健康状况不佳，官员们决定给它注射致命的一针。故选C。
2.What can we know about Grizzly 168?
A It was a new brown bear species in the field of biology.
B It became the key research object in animal laboratory.
C It partly helped grizzly bears to restore the population.
D It appeared in Yellowstone National Park 34 years ago.
解析：选C。推理判断题。根据第一段He did his part to help the population of bears recover. In his lifetime, researchers estimate he fathered at least three groups of baby bears.可知，这只灰熊尽了自己的一份力量帮助熊的种群恢复。研究人员估计，在他的一生中，他至少生了三组幼熊。故选C。
3.What had a great influence on Grizzly 168’s health?
A The lack of its favourite food.
B The loss of most of its teeth.
C The changes in eating habits.
D The decrease of the tree lands.
解析：选B。推理判断题。根据第三段内容This old bear, however, was not able to eat much. He was so old that he had lost most of his teeth. Grizzly 168 was so old that it only had three remaining teeth.可知，这只老灰熊吃不下多少东西。他年纪太大了，大部分牙齿都掉了，只剩下三颗牙。由此推断大部分牙齿的脱落严重影响了这只老熊的健康。故选B。
4.What does the last paragraph imply?
A Man has taken up all the areas of North America.
B It is false that humans and grizzly bears can live in peace.
C Grizzly bears will become extinct without their habitats.
D The number of grizzly bears dropped due to human activities.
解析：选D。推理判断题。根据最后一段Hundreds of years ago, there were lots of grizzly bears in North America. But as land was developed, many bears were killed.可知，几百年前，北美有很多灰熊。但随着土地的开发，许多熊被杀。由此推断由于人类活动，灰熊的数量减少了。故选D。
