21、
4.The risk of dying from cancer in developed countries is
a)double that in developing countries.
b)much higher than that in developing countries.
c)the same as that in developing countries.
d)much lower than that in developing countries.
5.All the following factors may increase cancer rates EXCEPT
a)occupational carcinogens.
b)lack of access to tobacco.
c) unhealthy habits.
d)aging populations.
标准答案： D,A
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第二篇
New attempts to eradicate AIDS virus;
A high-profile attempt to eradicate the AIDS virus in a few patients continues to show promise.
But researchers won’t know for a year or more whether it will work, scientist David Ho told journalists here Wednesday for the Fourth Conference in Viruses and Infections.
“This is a study that’s in progress,” says Ho, head of the Aaron Diamond AIDS Research Center, New York.
The study involves 20 people who started combinations of anti-HIV drugs very early in the course of the disease, within 90 days of their infections. They’ve been treated for up to 18 months. Four others have dropped out because of side effects or problems complying with the exacting drug system.
The drugs have knocked the AIDS virus down to undetectable levels in the blood of all remaining patients. And, in the latest development, scientists have now tested lymph nodes and semen from a few patients and found no virus reproducing there, Ho says. “Bear in mind that undetectable does not equal absent,” Ho says.
Ho has calculated that the drugs should be able to wipe out remaining viruses – at least from known reservoirs throughout the body – in two to three years. But the only way to prove eradication would be to stop the drugs and see if the virus comes back. On Wednesday, Ho said he wouldn’t ask any patient to consider that step before 2 1/2 years of treatment.
And he emphasized that he is not urging widespread adoption of such early, aggressive treatment outside of trials. No one knows the long-term risks.
But other scientists are looking at similar experiments. A federally funded study will put 300 patients on triple-drug treatments and then see if some responding well after six months can continue to suppress the virus on just one or two drugs, says researcher Douglas Richman of the University of California, San Diego. Some patients in that study also may be offered the chance to stop therapy after 18 months or more, he says.
练习：
1.According to the passage, the attempt to eradicate the AIDS virus.
A. continues to be hopeful.
B. will be successful in a year.
C. will be successful in future.
D. will stop being hopeful.
2.Which is NOT true about the study?
A.There are 20 patients involved in the study.
B.The patients have used several anti-HIV drugs.
C.The patients have been treated for up to 18 months.
D.16 patients did not go through the whole study.
3.What do Ho’s words “Bear in mind that undetectable does not equal absent” mean?
A. AIDS virus can exist in the blood without being detected.
B. AIDS virus is undetectable in the blood.
C. No AIDS virus can be detected in the blood.
D. No virus found in the blood means no AIDS.
标准答案： A,D,A
23、
4.How could we prove that the drugs have wiped out the remaining viruses?
A.By using up all the drugs at once.
B.By waiting for the virus to die slowly.
C.By asking the patients’ feeling about the disease.
D.By stopping the drugs to see if the virus comes back.
5.Other scientists are looking at experiments that are similar in that they are
A. costly
B. economical.
C. traditional
D. bold.
标准答案： D,D
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