American researchers have developed a technique that may become an important tool in fighting AIDS．The technique stops the AIDS virus from attacking its target-cells in the body's defense system．When AIDS virus enters the blood, it searches for blood cells called T4 lymphocytes（淋巴细胞）．The virus connects to the outside of T4 lymphocytes, then forces its way inside．There it directs the cells' genetic（基因的） material to produce copies of the AIDS virus．This is how AIDS spreads.

Researchers think they may be able to stop AIDS from spreading by preventing virus from connecting to T4 cells．When AIDS virus finds a T4 cell, it actually connects to a part of the cell called CD4 protein.

Researchers want to fool the virus by putting copies or clones of the CD4 protein into the blood．This way the AIDS virus will connect to the cloned protein instead of the real ones．Scientists use the genetic engineering methods to make the clones．Normally a CD4 protein remains on the T4 cell at all times．The AIDS virus must go to it.

In a new technique, however, the cloned CD4 protein is not connected to a cell．It floats freely, so many more can be put into the blood to keep the AIDS virus away from real CD4 proteins on T4 cells．One report says the AIDS virus connects to the cloned proteins just as effectively as to real protein．That report was based on tests with blood cells grown in labs．The technique is just now beginning to be tested in animals．If successful, it may be tested in humans within a year.

1．The new technique can ________.

       A．kill the AIDS virus

       B．produce new anti-AIDS cells

       C．produce new medicines for AIDS

       D．prevent the AIDS virus from spreading

2．When the AIDS virus enters the blood, it is reproduced by ________.

       A．any blood cells in the body

       B．the inside of the virus itself

       C．the genetic material of T4 cells

       D．the outside of the T4 lymphocytes

3．The AIDS virus connects to cloned proteins instead of to the real ones because ________.

       A．the cloned proteins stay on the T4 cells

       B．the cloned proteins can float freely in the blood

       C．the cloned proteins are the same as the real proteins

       D．the cloned proteins are made by genetic engineering methods

4．Which of the following could be the best title of this passage?

       A．The Genetic Causes of AIDS.

       B．A New Approach of Fighting AIDS.

       C．A Report on the Spread of AIDS Virus.

       D．The Technique of Cloned CD4 Protein.

   On June 5, 1981 the Centers for Disease Control in Atlanta, U.S. announced the presence of a rare, infectious disease in five American homosexuals(同性恋). Soon doctors were finding similar cases all over the country and the world. The AIDS epidemic(流行病)had officially begun. By 1983 it was clear that AIDS had spread around the world. More than twenty years later, AIDS has left twenty-six million dead and another forty million infected.  AIDS has become the worst medical disaster ever experienced by mankind.

   Hundreds of young people between the ages of 20 and 45 died each week during the early years of the U.S. AIDS. More than 600,000 cases of AIDS have been reported since 1981 in the United States, and it is estimated that there may be as many as 900,000 Americans infected with HIV.

   Though the rate of HIV infections continues to increase in the United States, the number of AIDS cases has fallen sharply since 1996, when antiretroviral drugs came onto the market. Unfortunately, the AIDS epidemic continues today in Africa and much of Asia, where antiretroviral treatment is not available and health care is far from enough. AIDS is the fourth leading cause of death worldwide, and the No. 1 cause of death due to infectious disease.

   HIV, the virus that causes AIDS, was first separated in 1983 by a team at the Pasteur Institute in Paris. That discovery made it possible to develop a test for AIDS and trace back to victims who may have died before doctors were aware of the disease.

   However, scientists still don't know exactly how and where AIDS started. Finding the source of AIDS could be important in developing a vaccine(疫苗) and be important in mapping the future course of the epidemic.

31. It can be inferred from the passage that        

     A. antiretroviral drugs will be obtained easily all over the world

     B. the best way to stop AIDS is to develop a vaccine

     B. scientists will soon find a way to cure AIDS

     D. there will be fewer AIDS cases in the world in the future

32. Which areas are the most worrying places where AIDS spreads quickly?

     A. Africa.           B. Asia.              C. The United States.      D. France.

33. The number of AIDS cases has greatly decreased in the United States due to the fact

     A. a team at the Pasteur Institute in Paris succeeded in separating HIV

     B. some effective medicine has been invented

     B. scientists understand AIDS better and better.

     D. The rate of HIV infections continue to rise in the United States

34. What's the importance of the discovery of the source of AIDS?

     A. It can be used to develop a test for AIDS.

     B. It can stop HIV forming AIDS.

     B. It can reduce the rate of death caused by AIDS.

     D. It can help develop a drug to prevent AIDS.

35. When did the name of AIDS come into being?

     A. In 1983.           B. In 1981.           C. In 1996.           D. In 1994.