killed a large percentage of the park's red foxes, and completely drove away the park's beavers.

　　As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many farmers opposed the plan because they feared that wolves would kill their farm animals or pets.

The government spent nearly 30 years coming up with a plan to reintroduce the wolvers. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. Elk, deer, and coyote populations are down, while beavers and red foxes have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.

28. What is the text mainly about?

　A. Wildlife research in the United States.

　B. Plant diversity in the Yellowstone area.

　C. The conflict between farmers and gray wolves.

　D. The reintroduction of wolves to Yellowstone Park.

29. What does the underlined word ＂displaced＂ in paragraph 2 mean?

A. Tested. B. Separated.

C. Forced out. D. Tracked down.

30. What did the disappearance of gray wolves bring about?

　A. Damage to local ecology. B. A decline in the park's income.

　C. Preservation of vegetation. D. An increase in the variety of animals.

31. What is the author's attitude towards the Yellowstone wolf project?

A. Doubtful. B. Positive.

C. Disapproving. D. Uncaring.

　　【文章大意】本文是一篇说明文，介绍了美国黄石公园重新引进灰狼的事情。人类活动的影响使灰狼的数量逐渐减少，鹿群数量逐渐增加，从而导致植被被大量破坏。

30. A 【解析】推理判断题。根据第三段的内容可知，灰狼的减少造成了鹿群的增多，从而植被遭到了破坏