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.

阅读理解

　　The dark smoke that comes out of stacks (烟囱) or from a burning dump (垃圾) contains tiny bits of solid or liquid matter. The smoke also contains many gases, most of which cannot be seen. Altogether, they make up the serious problems of air pollution. In so many places it keeps us from seeing the sun, irritates (刺激) our eyes, causes us to cough, and makes us ill.

　　Air pollution can spread from city to city. It even spreads from one country to another. Some northern European countries have had “black snow” from pollutants that have traveled through the air from other countries and have fallen with the snow. So, air pollution really is a global (全球性的)problem.

　　Air pollution can kill babies, older people, and those who have respiratory (呼吸的) diseases, In London, in 1952, four thousand people died in one week as a result of a serious air-pollution episode (一连串事件中的一个). In 1948, in the small town of Donora, Pennsylvania, twenty people died in a four-day period of bad air pollution.

　　At levels (平原) often found in cities, air pollution increases the risks of certain lung diseases, of course, smoking and other factors help to cause these illnesses, too, but these cases have increased greatly during recent years as air pollution has become worse.

　　Air pollution can cause both airplane and auto accidents because it cuts down visibility (能见度). There are other possible health dangers from air pollution that we don’t know much about. For example, scientists are trying to find out whether chemicals that reach us from the air may cause changes in our cells. These changes might cause babies to be horn with serious birth defects (缺陷，缺点). Scientists are trying to learn how all the many chemicals we are apt to take into our bodies from air, water, food, and even medicines act together to affect our health and the way our bodies work. That is another reason why it is so important to begin to control pollution now instead of waiting until we learn all the answers.

　　Air pollution costs us a lot of money. It corrodes (腐蚀)our buildings. It damages farm crops and forests. It has a destructive (毁灭性的) effect on our works of art. The cost of all this damage to our government is astronomical (极大的). It would be much more worth while, both for us and for the environment, to spend our tax dollars on air pollution control.

1．The direct cause of air pollution is ________.

[　　]

A．dark smoke from stacks or a burning dump

B．tiny bits solid or liquid matter

C．lots of invisible gases

D．chemicals in the air

2．Which of the following is NOT the bad effect of air pollution?

[　　]

A．Keeping us from seeing the sun.

B．Killing babies and older people.

C．Spreading diseases.

D．Causing car accidents.

3．The reason why air pollution can cause plane accidents is that ________.

[　　]

A．it irritates our eyes

B．it causes us to cough

C．it keeps us from seeing clearly

D．it increases the risks of lung diseases

4．Some babies are born with serious illness because of ________.

[　　]

A．black snow

B．respiratory diseases

C．chemicals in the air

D．damage to crops and forests

5．The purpose of the passage is to ________.

[　　]

A．explain what is air pollution

B．show how terrible air pollution is

C．discuss whether air pollution can cause changes in our cells

D．persuade people to spend mere money on air pollution control

Life has changed in Mexico City. Streets normally filled with people are empty. One of the most popular professional soccer teams recently played a game in an empty stadium that can seat more than 100,000 people. It's swine (猪) flu that has made life in Mexico City grind to a halt (慢慢停了下来)

Seemingly out of nowhere, swine flu has caused confirmed deaths in 12 countries as of April 30. It has sent a wave of alarm around the world. Governments are trying to find ways to prevent further outbreaks. The World Health Organization has raised its swine flu global threat level to five out of six.

People may be familiar with bird flu. but they know little about swine flu.O Swine flu is a contagious (传染性的) respiratory (呼吸的) disease in pigs. It is caused by a type-A influenza virus.

Humans can also catch swine flu. The virus causes regular outbreaks in pigs, but people usually do not catch it. However, there have been cases of the virus spreading to people, and then from one person to another.

The symptoms of swine flu are similar to the common flu. They include fever, lethargy (无精打采的), lack of appetite, coughing, runny nose, sore throat, nausea (恶心), and vomiting (呕吐). The high proportion of young adults among the deaths is one of several mysteries about this virus. Most of the dead had lung damage. What caused it is not yet known.

The virus spreads the same way the common flu does. When an infected person coughs or sneezes around another person, the latter is put at risk. People can get the disease by touching something with the flu virus on it and then "touching their mouth, nose or eyes.

There are medicines to treat swine flu. Doctors suggest using anti-viral drugs. They keep the virus from reproducing inside the body.

Although there are no vaccines (疫苗)for it now, several everyday steps can help prevent the spread of the virus: washing hands frequently; avoiding close contact with people who are sick; and avoiding touching surfaces that might have the virus on it.

People may worry that they will get swine flu from eating or preparing pork. In fact, you cannot catch the virus from pork products if they have been properly prepared and cooked. Cooking food at temperatures of 71^oC kills the virus.                 

56. The main idea of the passage is __________________.
A. how swine flu broke out in Mexico City.      B. some information concerning swine flu.
C. the differences between swine flu and bird flu. D. the dangers caused by swine flu.
57. The following tips can protect us from swine flu EXCEPT ________.
A. keeping us away from other people
B. washing hands frequently
C. avoiding close contact with sick people
D. avoiding touching surfaces that might have the virus on them
58. What’s the main idea of the first paragraph?
A. Mexico City is really a place of horror now.
B. People in Mexico City like staying at home.
C. People in Mexico City don’t like soccer.
D. Swine flu has seriously affected people’s life in Mexico City.
59. What can we conclude from the passage?
A. The swine flu virus causes regular outbreaks among people.
B. People usually get infected with swine flu directly from pigs.
C. All animals including pigs can easily be infected with swine flu.
D. People usually do not catch swine flu though it is a danger to people.
60. What can we infer from the passage?
A. At present there still aren’t effective vaccines for swine flu.
B. Swine flu virus cannot spread in the air.
C. From now on, people can’t eat pork if they want to be safe.
D. All of the dead killed by swine flu had lung damage.