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  3. Excerpt 1 The process of vaccination allows the patient’s body to develop immunity to the virus or disease so that, if it is

Excerpt 1 The process of vaccination allows the patient’s body to develop immunity to the virus or disease so that, if it is

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问题 Excerpt 1
    The process of vaccination allows the patient’s body to develop immunity to the virus or disease so that, if it is encountered, one can ward it off naturally.To accomplish this, a small weak or dead strain of the disease is actually injected into the patient in a controlled environment, so that his body’s immune system can learn to fight the invader properly.Information on how to penetrate the disease’s defenses is transmitted to all elements of the patient’s immune system in a process that occurs naturally, in which genetic information is passed from cell to cell.
Excerpt 2
    Scientists are hoping to eliminate malaria (疟疾) by developing a genetically modified mosquito that cannot transmit the disease.Malaria has long troubled the populations of South America, Africa, and Asia, where mosquito bites infect to 500 million people a year with this serous and sometimes fatal parasitic blood disease. For generations, scientists have been trying to eliminate malaria by developing new drugs and using pesticide (杀虫剂) to wipe out local mosquito populations.But these measures aren’t working...and some scientists, like Greg Lanzaro, say that because of drug resistance and population changes, malaria is actually more prevalent now than it was 20 years ago.
Excerpt 3
    Most diseases involve the death of healthy cells—brain cells in Alzheimer’s, cardiaccells in heart disease, pancreatic cells in diabetes, to name a few if doctors could isolate stem cells, then direct their growth, they might be able to furnish patients with healthy replacement tissue.
Excerpt 4
    The prospective rewards of gene therapy are tremendous:the suppression and even prevention of inherited disease.At present, gene therapy is being directed at somatic cells, the working cells in a human body that do not pass on genes to the next generation.Therapy someday will be directed at germ cells sperm and egg cells and their precursors that do transmit genetic information to the next generation.Such therapy would remove, replace, or alter the genes that cause inherited diseases.However, mistakes in germ-line gene therapy could cause extreme deficiencies and horrendous mutations.This is an area of medical research in which work must progress with
great care.No errors can be tolerated.
Excerpt 5
    From the health point of view we are living in a marvelous age.We are immunised from birth against many of the most dangerous diseases.A large number of once fatal illnesses can now be cured by modern drugs and surgery.It is almost certain that one day remedies will be found for the most stubborn remaining diseases.
Excerpt 6
    Cardiologists have pioneered the world’s first non-surgical bypass operation to turn a vein into an artery using a new technique to divert blood flow in a man with severe heart disease; the keyhole procedure, which avoids the extensive invasive surgery of a conventional bypass,will offer hope to tens of thousands of people at risk from heart attacks.
    Coronary heart disease, where the arteries are progressively silted up with fatty deposits, is responsible in a major industrial country like Britain for more than 160,000 deaths each year.Although major heart surgery is becoming commonplace, with more than 28,000 bypass operations in the UK annually, it is traumatic for patients and involves a long recovery period.
One reason for malaria to be more widespread now is that______.
选项 A、more people have moved to malaria-infected areas
B、mosquitoes have become resistant to pesticides
C、genetically modified mosquitoes still transmit the disease
D、mosquitoes bite as many as 500 million people a year
答案B
解析 在Excerpt 2讲到，科学家希望使蚊子不能传播疾病来消除疟疾。后面讲到“because of drug resistance and population changes，malaria is actually more prevalent now than it was 20 years ago．”由于蚊子的抗药性和人口的变化，现在，疟疾实际上比20年前更普遍。可见A项不符合文意，B项“蚊子对杀虫剂有抵抗力”正确。
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