单选题Narrator Listen to part of a lecture about the environment study in Biramichi River. Now get ready to answer the questions. You may use your notes to help you answer.

单选题Many species of (birds) that (breed in) temperate latitudes often show (particular) patterns of migration (while) the year.

单选题Whydoesthewomangotoseeherprofessor?A.Shewantstogetmaterialsforaclassshemissed.B.Shewantstodiscussanassignmentsheisworkingon.C.Theprofessorwantstotellheraboutherscholarship.D.Shewantstoinformtheprofessorofchangesinherschedule.

单选题It is said that United Stales literature ...... individuality and identity in the twentieth century, after long imitation of European models. (a)was achieved (b)achieved (c)to achieve (d)achieving

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单选题The function of the glass in the first flashbulbs was to

单选题Listening8"LiteratureClass"

单选题Which of the following is NOT true of the Native American literature discussed in the passage?

单选题Caves are formed by the chemical or action mechanical of water on soluble A B rock, by volcanic activity, and by earthquakes. C D

单选题The word "marked" in line 7 is closest in meaning to

单选题According to the passage, how did later mills differ from the mills differ from the mill built by Oliver Evans?

单选题According to the passage, what responsibility does the audience of a verbal art performance have?

单选题Many of the fine-grained varieties of sedimentary rocks known as shales yield oil when distilled by hot.

单选题In ______ people, the areas of the brain that control speech are located in the left hemisphere.

单选题Coming Soon: the Next Great Flu Epidemic The virus first came to officials' attention in a bag of dead chickens. Early in March 1997, a farmer from Hong Kong's New Territories carried them into the Agriculture and Fisheries Department laboratory. The final state of some birds was a hideous, bloody mush. Cultures of their organs revealed they had died of avian influenza, type H5N1. Influenza of the H5 subtype had never been known to infect humans. But in the next seven months, 18 Hong Kong residents fell ill with H5N1 and six died. In late December 1997, public health officials took a drastic step, ordering the slaughter of every chicken in every farm and marketplace in Hong Kong. The HSN1 virus seemed to disappear but for how long? The specter of the 1918 flu was raised by this new avian flu. The 1918 flu was one of the most changeable and resistant viruses known to man. After we've been infected with one strain, it can mutate and infect us again. We are only immune to flu strains our bodies have seen before. A flu can also "jump species" to an animal it has never infected before, once such a flu moves into humans, if it can "learn" to pass easily between them, it can spark a pandemic—a global outbreak. Birds carry the flu virus in their intestines and excrete it in their feces. In all likelihood, shoppers who got sick with H5 touched surfaces contaminated with chicken feces. Humans, however, carry flu in their respiratory tracts and usually spread them in a cough or sneeze. Flu strains that travel this way are highly contagious. The H5 virus in Hong Kong was different. It sickened very few, but killed a third of those infected. Most who got sick with H5 seemed to catch it directly from a bird they bought in a live-poultry market. After the Hong Kong outbreak, flu experts feared that H5—already deadly to humans—might learn to move between humans as well as between birds. That "raises the specter of 1918", says Nancy Cox, chief of the Influenza Branch of the U. S. Centers for Disease Control and Prevention (CDCP). Geographic isolation was no protection during the 1918 pandemic. In the Alaska Territory, the mortality rate in some villages was as high as 90 percent. All told, at least 500000 Americans perished. It could happen again. The virus that became the Spanish flu probably came from a bird. Avian-flu expert Dr. Robert Webster of St. Jude Children's Research Hospital in Memphis, Tenn., believes the virus may have leapt straight from birds to humans, possibly a year to two before the pandemic began. Once lodged in human lungs, it quickly passed from person to person in a simple cough or sneeze. To avoid that grim possibility, here are three measures all nations need to take: The first step is better surveillance. Most countries, though, don't start tracking avian flu until after an epidemic kills their chickens. The United States dramatically increased its monitoring after a deadly outbreak in Pennsylvania in the early 1980s. The USDA (United States Department of Agriculture) provides diagnostic support. Some virologists recommend enhancing surveillance of swine flu too. The U. S. National Institutes of Health is beginning to study the issue. Elsewhere, the coverage is not good enough, says Dr. W. Paul Glezen of the Baylor College of Medicine's Influenza Research Center. He names Africa and South America as areas where the World Health Organizations net is incomplete. Another important measure is producing more vaccines and flu shots. Only three of the 15 known influenza subtypes—H1, H2 and H3—have been found in people. Vaccines exist for each, and an H5 vaccine is now being developed. Some experts believe that we should develop a vaccine for the other known subtypes as well. Health authorities add that more people need flu shots now. We should manufacture 120 million doses a year, but we are making only 80 million. If we bought more vaccines, manufacturers could produce more. This increased production capacity would be invaluable in a pandemic. A strong pandemic plan. The U. S. government has been developing a pandemic plan since 1997. The Hong Kong outbreak, notes CDCP investigator Keiji Fukuda, was a "dry run" for a real emergency. "It showed us we can get people there and answer some tough questions," but "H5 also taught us that lots of issues are hard to grapple with they come so fast". In March of this year, Hong Kong's Agriculture and Fisheries Department announced it had found H5N1 in the goose excrement of a poultry stall.(A) [■] The virus was not identical to the 1997 version, and the next day it was gone.(B) [■] However, the two viruses were related.(C) [■] A month later, in April, the Hong Kong Department of Health announced that two girls, ages one and four, were recovering from an H9 flu virus found in poultry.(D) [■] H9 has never before been known to infect humans.

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单选题The word "it" in line 24 refers to