C

After years of heated debate, gray wolves werereintroduced to Yellowstone National Park. Fourteen wolves were caught inCanada and transported to the park. By last year, the Yellowstone wolfpopulation had grown to more than 170 wolves.

Gray wolves once were seen here and there in theYellowstone area and much of the continental United States, but they weregradually displaced by human development. By the 1920s, wolves hadpractically disappeared from the Yellowstone area. They went farther north intothe deep forests of Canada, where there were fewer humans around.

Thedisappearance of the wolves had many unexpected results. Deer and elkpopulations — majorfood sources (来源) forthe wolf – grew rapidly. These animals consumed large amounts of vegetation (植被), which reduced plant diversity in the park. In theabsence of wolves, coyote populations also grew quickly. The coyotes killed a largepercentage of the park’ s red foxes, and completely drove away the park’ sbeavers.

As early as 1966,biologists asked thegovernment to consider reintroducing wolves to Yellowstone Park.They hoped thatwolves would be able to control the elk and coyote problems.Many farmersopposed the plan because they feared that wolves would kill their farm animalsor pets.

    The government spent nearly 30 years comingup with a plan to reintroduce the wolvers. The U.S.Fish and Wildlife Servicecarefully monitors and manages the wolf packs in Yellowstone.Today,the debatecontinues over how well the gray wolf is fitting in at Yellowstone.Elk,deer,andcoyote populations are down,while beavers and red fores have made acomeback.The Yellowstone wolf project has been a valuable experiment to helpbiologists decide whether to reintroduce wolves to other parts of the countryas well.

28.What is thetext mainly about?

A.Wildliferesearch in the United States.

B.Plant diversityin the Yellowstone area.

C.The conflictbetween farmers and gray wolves.

D.Thereintroduction of wolves to Yellowstone Park.

29.What does theunderlined word “displaced” in paragraph 2 mean?

A.Tested.        B.Separated.          C.Forced out.         D.Trackeddown.

30.What did thedisappearance of gray wolves bring about？

A.Damage to localecology.     B.A decline in the park’sincome.

C.Preservation ofvegetation.    D.An increase in thevariety of animals.

31.What is theauthor’s attitudetowards the Yellowstone wolf project？

A.Doubtful.       B.Positive.      C.Disapproving.      D.Uncaring.