The year was 1959.Location: The central African city of Leopoldville, now
called Kinshasa, shortly before the waves of violent rebellion that followed the liberation of the Belgian Congo.A seemingly healthy man walked into a hospital clinic to give blood for a Western-backed study of blood diseases.He walked away and was never heard from again.Doctors analyzed his sample, froze it in a lest tube and forgot about it.A quarter-century later, in the mid-1980s, researchers studying the growing AIDS epidemic took a second look at the blood and discovered that it contained HIV, the virus that causes AIDS.
And not just any HIV.The Leopoldville sample is the oldest specimen of the AIDS virus ever isolated and may now help solve the mystery of how and when the virus made the leap from animals(monkeys or chimpanzees)to humans, according to a report published last week in Nature.Dr.David Ho, director of the Aaron Diamond AIDS Research Center in New York City and one of the study’s authors, says a careful genetic analysis of sample’s DNA pushes the putative origin of the AIDS epidemic back at least a decade, to the early 1950s or even the 1940s.
Over the past 15 years, scientists have identified at least 10 subtypes of the AIDS virus.But they couldn’t tell whether they were seeing variations on one changeable virus or the handiwork of several different viruses that had made the jump from primates to man.A close look at the genetic mutations in the Leopoldville sample strongly suggests that all it look to launch the AIDS epidemic was one unlucky turn of events.
By comparing the DNA of the 1959 virus with that of samples taken from the 1980s and 1990s , Ho and his colleagues constructed a viral family tree in which the Leopoldville isolate sits right at the juncture where three subtypes branch out.The 39-year-old specimen is also strikingly similar to the other seven subtypes.The clear implication: all the viral strains can be traced back to a single event or a closely related group of events.One theory is that AIDS started through contact with infected monkeys in a remote area and spread to the rest of the population through urbanization and mass inoculations.
The findings underscore how rapidly HIV can adapt to its surroundings, making it devilishly difficult to develop effective vaccines.No one knows how many more subtypes of HIV will sprout in the next 40 years, but chances are that they will be every bit as lethal as the ones we see today, if not more so.
36.What does the phrase “Belgian Congo” mean?
A.Belgium was a colony of Congo.
B.Congo was a colony of Belgium.
C.Belgian Congo was a African state.
D.Belgium and Congo were two separate countries.
37.According to this article, HIV in human body originated from .
A.animals B.plants
C.food D.Not mentioned in the article
38.Are the ten subtypes of the AIDS virus variation of one?
A.Yes. B.No.
C.Scientists are not sure about it at present.
D.It is not mentioned in the article.
39.Which of the following statements is true?
A.All the viral strains can be traced back to a single event.
B.HIV can not easily adapt to its surroundings.
C.AIDS started through contact with inflected monkeys in a remote area.
D.AIDS started through urbanization and mass inoculations.
40.Which of the following is the best topic for this passage?
A.How to Protect Yourself from AIDS?
B.Where Does HIV Come From?
C.Classification of HIV.
D.When Did AIDS Begin?
第1题
By Jennifer Lim
Staff Reporter
The City of Newtonville has announced it will sponsor summer events in City Park starting June 18.
Entitled Newtownville Summer Sizzlers, the events are aimed at bringing together families and neighbors during the summer months. "We hope to bring Newtonville citizens out of the house, away from the televisions and video games, and into nature," said Mayor Charles Adams. "Summer used to be a time for families to spend together and for children to play outside with their friends in the park. Now, everyone just stays at home."
The city has scheduled events such as barbecues, picnics, free concerts, and even games for the children. Local businesses will also have food stands and crafts available for sale. "This will be a great social event for our residents, marketing opportunity for our businesses, and welcoming for our new residents," said councilmember Roberta Rogers.
The event will be held every Saturday from 4-9 p.m. until the last weekend in July. Although food will be for sale during the events, residents are welcome to bring their own.
"We used to have summer activities when 1 was young," said 72-year-old Grace Keller, who was born and raised in Newtonville. "You can bet I will be out at least a few times to spend time with my neighbors."
A list of the performances and other scheduled events is available on the city Web site at www.newtonville.org/summersizezler.
Who will sponsor the event?
A.The city
B.Local businesses
C.Volunteer residents
D.A civic organization
第2题
A.Because they are bred there.
B.Because they need swim upstream to multiply.
C.Because they were brought there by flood.
D.Because people farm salmon in this river for its delicious taste.
第3题
A.The previous fare increase was the same amount as the proposed fare increase.
B.Fare increases do not necessarily lead to lower revenues from city bus service.
C.A decrease in fares would result in increased ridership and increased revenues from bus service.
D.The fare increase would make Greenville" s bus service much more expensive than bus services in other comparable cities.
E.Some of the people currently using the bus have the option of not traveling by bus.
第4题
M: Yes. I was horn here at Vegetable Creek Hospital.
W: Right, so Emma Ville used to be called Vegetable Creek.
M: That's correct.
W: When did they change the name, do you know?
M: They changed the name back in 1872.
W: Right, and why was that?
M: It was because at the time the governor of New South Wales was, his wife's name was Emma, and he came to Emma Ville and opened up the Emma Ville hospital and he called it Emma Ville, after Emma.
W: And there used to be a lot of Chinese people growing vegetables here before.
M: That's fight. There were 3,000 Chinese at a tin mine in Emma Ville. Emma Ville used to produce 400,000 tons of tin a year. The last mine that was in Emma Ville closed down in 1988.
W: And what year were you born?
M: I was born the first of November, 1942. And I've worked among sheep and machinery all my life.
W: So what was it like growing up around here?
M: Quite good. I still retain my keen memory of my early events that occurred in Emma Ville, and those unforgettable days. I'd really like to do it all back over again.
W: When did you start running sheep?
M: Back in 1979.@I never had one acre of ground. I leased country then, in 1979, out in this area, and built myself the sheep farm from there.
W: Do you shear your own sheep or...?
M: No. No, I pay shearers.
(20)
A.He is American.
B.He is Austrian.
C.He is Australian.
D.He is English.
第5题
??A patient on the brink ofdeath has received the world's first self-contained artificial heart-a bat-tery powered device about the size of a softball that runs without the need forwires, tubes or hoses sticking out of the chest.????
?? Two surgeons from the University of Louisvilleimplanted the titanium and plastic pump during a seven-hour operation at JewishHospital Monday. The hospital said the patient was "awake andre-sponsive" Tuesday and resting comfortably. It refused to releasepersonal details.
?? The patient had been expectedto die within a month without the operation, and doctors said they expected theartificial heart to extend the person's life by only a month But the device isconsidered a major step toward improving the patient's quality of life.??
?? The new pump, called AbioCor, is also a technological leap from the mechanical hearts used in the 1980s,which were attached by wires and tubes to bulky machinery outside the body. Themost fa- mous of those, the Jarvic-7, used air as a pumping device and wasattached to an apparatus about the size of a washing machine.??
?? "I think it'spotentially a major step forward in the artificial heart development,"said Dr. David Faxon, president of the American Heart Association. However, hesaid the dream of an implantable, permanent artificial heart is not yet areality: "This is obviously an experimental device whose long-term successhas to be demonstrated. " Only about half of the 4, 200 Americans on awaiting list for donor hearts receivedthem last year, and most of the rest died:??
?? Some doctors, includingRobert Higgins, chairman of cardiology at the Medical Colle??ge of Virgin-ia in Richmond, said artificial hearts are unlikely to replacedonor hearts.
?? "A donor heart in a goodtransplant can last 15 t0 30 years, " he said. "It's going to be hardto re-place that with a machine. "
?? The Abil Cor has a 2-poundpumping unit, and electronic controls that adjust the pumping?? speed based onthe body's needs. It is powered by a small battery pack worn outside the bodythat transmits current through the skin.
The pump of the first implanted self-contained heart was made of titanium andplastic????????????
A.Right
B.Wrong
C.Not mentioned
第6题
Her love for poetry began early. At the age of seven, she "began to put rhymes together" , and when she was thirteen, one of her poems was published in a children's magazine. During her teens she contributed more than seventy-five poems to a Chicago newspaper. In 1941 she began to attend a class in writing poetry at the South Side Community Art Center, and several years later, her poems began to appear in Poetry and other magazines. Her first collection of poems. A Street in Bronzeville was published in 1945. Four years later, Annie Allen, her second collection of poems, appeared. In 1950, Annie Allen was awarded a Pulitzer prize for poetry. A novel, Maud Martha, about a young Black girl growing up in Chicago, published in 1953, was praised for its warmth and insights. In 1963, her Selected Poems appeared.
The main subject of the passage is Gwendolyn Brooks's ______.
A.personal background
B.literary achievements
C.hometown
D.childhood
第7题
Her love for poetry began early. At the age of seven, she "began to put rhymes together", and when she was thirteen, one of her poems was published in a children's magazine. During her teens she contributed more than seventy-five poems to a Chicago newspaper. In 1941 she began to attend a class in writing poetry at the South Side Community Art Center, and several years later, her poems began to appear in Poetry and other magazines. Her first collection of poems. A Street in Bronzeville was published in 1945. Four years later, Annie Allen, her second collection of poems, appeared. In 1950, Annie Allen was awarded a Pulitzer prize for poetry. A novel, Maud Martha, about a young Black girl growing up in Chicago, published in 1953, was praised for its warmth and insights. In 1963, her Selected Poems appeared.
The main subject of the passage is Gwendolyn Brooks's ______.
A.personal background
B.literary achievements
C.hometown
D.childhood
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