An annual census of wolves at Yellowsto ne National Park has found a sharp drop in the population. But park biologists, who suspect a deadly disease, canine parvovirus, say they will let nature take its course. "Parvo can be vaccinated for and can be treated, but we wouldn’t do it because we couldn’t catch every animal," Daniel Stahler. a park waif biologist, said. "And this allows them to build up a natural resistance."
The census found 22 pups, compared with 69 last year. The total count of wolves dropped m 118 from 171, the lowest since 2000. "It was somewhat devastating to have such poor pup survival," Mr. Stahler said. "But research shows that young pups can bounce back from it quite successfully." That pups have suffered the decline seems to suggest the culprit is parvo, said Ed Bangs, waif recovery coordinator for the United States Fish and Wildlife Service here. Nursing pups receive immunity from their mother&rsq
A. they will vaccinate the wolves
B. they have no method to deal with the disease
C. they will build up a natural resistance
D. they will not take any measure
The Library of Congress is America’s national library. It has millions of books and other objects. It has newspapers and popular publications, as well as letters of historical interest. It also has maps, photographs, art prints, movies, sound recordings, and musical instruments. All together, it has more than 100 million objects. The Library of Congress is open to the public Monday through Saturday except for public holidays. Anyone may go there and read anything in the collection. But no one is permitted to take books out of the building. The Library of Congress was established in 1800. It started with 11 boxes of books in one room of the Capitol Building. By 1814, the collection had increased to about 3,000 books. They were all destroyed that year, when the Capitol was burned down during America’s war with Britain. To help rebuild the library, Congress bought the books of president Thomas Jefferson. Mr. Jefferson’s collection included 7,000 books in seven lang
我来回答: