4.    The paragraph following the passage most probably discuss _______

A.    The prevention of HIV transmission

B.    AIDS indifferent countries

C.    How the scientists make research on chimpanzees

D.    How DIDS transmit these years

Passage 83  Living a long life

In the Caucasus region of Russia, nearly 50 out of every 100,000 people live to celebrate their 100th birthday, and many don’t stop at 100! By comparison, in America only 3 people in 100, 000 reach 100. But these Russian old people aren’t alone. The Pakistanis, who live high in the Himalaya Mountains, and the Ecuadorans of the Andes Mountains seem to share the secret of long life, too.

These people remain healthy in body and spirit despite the passage of time. While many older persons in industrial societies become weak and ill in their 60s and 70s, some Caucasians aged 100 to 140, work in the fields beside their great-great-grandchildren. Even the idea of aging is foreign to them. When asked “at what age does youth end?” most of these old people had no answer. Several replied, “Well, perhaps at age 80.”

What accounts for this ability to survive to such old age, and to survive so well? First of all, hard physical work is a way of life for all of these long-lived people. They begin their long days of physical labor as children and never seem to stop. For example, Mr. Rustam Mamedov is 142 years of age. His wife is 116 years old. They have been married for 90 years. Mr. Mamedov has no intention of retiring from his life as a farmer. “Why? What else would I do?” he asks.

All these people get healthful rewards from the environment in which they work. They all come from mountainous regions. They live and work at elevations of 1,660 to 1,000 meters above sea level. The air has less oxygen and is pollution-free. This reduced-oxygen environment makes the heart and blood vessel system stronger.

Another factor that may contribute to the good health of these people is their isolation. To a great extent. They are separated from the pressures and worries of industrial society.

Inherited factors also play some role. Most of the longest-lived people had parents and grandparents who also reached very old ages. Good family genes may, therefore, be one factor in living longer.

It is clear that isolation from urban pressures and pollution, clean mountain air, daily hard word, moderate diets, good genes, and a youthful approach to life all contribute to the health and long life of all these people.

3.    Which of the following is not mentioned in the passage as one of the possible causes of why giving can save your life?

A.   Giving produces positive emotions.

B.    Helping others protects us against the negative effects of cardiovascular stress.

C.    Giving means getting in a manner of speaking.

D.   Giving strengthens our relations with others and makes us feel good.

Passage 82  The origin of Aids

Nothing comes of nothing, and so AIDS must come from something and, indeed, somewhere. A paper just published in nature provides what appear to be the answers to these questions. The disease spread to people from chimpanzees(黑猩猩) in equatorial Africa.

This result comes as little surprise. It has been known for years that HIV-S (the type of human immunodeficiency virus which causes most cases of AIDS) is, in effect, just another simian(猿) immunodeficiency(免疫缺陷) virus (SIV) of the sort that infect monkeys and apes. It was also known the AIVs most closely resembling HIV-1 are found in chimpanzees. (Another human AIDS virus, not that closely related, and known as HIV-2, comes from a monkey called the first cases of AIDS, including one that dated back to 1959 but was properly analyzed only a year ago, came from Africa, the strong presumption(假定) is that Africa is where the disease started.

But chimpanzee SIVs are. Until now, only three had been identified in laboratory animals of uncertain provenance. The discovery of the fourth case, by a team of researchers from America, Britain and France, led by Beatrice Hahn of the University of Alabama at Birmingham-together with a more detailed investigation of where each of the apes in question came from has cleared the details up.

The genetic material of the four chimpanzee SIVs suggests that three of them, including the new one, are closely related. The fourth belongs to a different branch of the SIV family tree. And by analyzing genes from the chimpanzees themselves, Dr. Hahn and her colleagues have shown that the three related SIVs come from a subspecies that lives mainly in Gabon, Cameroon and Equatorial Guinea. The outlying virus was found in a second sub-species that exists further east.

It is probably no coincidence that the part of Africa where the related SIVs come from is the only place on earth where all three of the basic types of HIV-1-known as M, N and O-- are found. Fortunately for the rest of humanity, only type M has spread from its homeland. The other two are still confined locally.

Analysis of the part of the SIV family tree containing the three related SIVs and the three basic types of HIV-1 shows that all six are close kin, and that the three types of HIV-1 seem to have had different origins within the western chimpanzee SIV group. That suggests the M, N and O strains each made an independent leap from chimp to man.

Other than sexual contact, the only way to transmit these viruses is via blood. The best guess, therefore, is that AIDS has spread to man as a result of people hunting chimpanzees for food----a practice, often bloody, that continues to this day.

Unfortunately, this hunting now risks exterminating the very population that infected humanity in the first place to find out why chimpanzees do not get ill from HIV-1, Where people do. Ironic, really.

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