The government is doing whatever they can to ____ the bird flu from spreading.

A. prevent                 B. promote                C. prepare                 D. predict

 It is ______ that all the governments should join hands to prevent H1Ni flu from spreading. Ks5u

A. essential         B. reliable            C. precious       D. traditional Ks5u

 It is ______ that all the governments should join hands to prevent H1Ni flu from spreading.  

A. essential         B. reliable            C. precious       D. traditional  

Flu is a common infection of the nose and throat, and sometimes the lungs. The cause is a virus that passes from one person to another. The virus spreads through the air when an infected person expels air suddenly.

　 Flu develops after the virus enters a person's nose or mouth. The flu causes muscle pain, sudden high body temperature, breathing problems and weakness. Generally, most people feel better after a week or two. But the flu can kill. It is especially dangerous to the very young, the very old and those with weakened defenses against disease.

　 Medical experts have recognized for some time that people become infected with flu during the winter months. But they did not really know why until recently.

American researchers say they now know why the flu virus spreads in the winter and not in the summer. They say it is because the virus remains in the air longer when the air is cold and dry.

Researchers in New York carried out twenty experiments with guinea pigs to investigate how the virus spreads. The researchers found the virus spread the most when the temperature was about five degrees Celsius and the humidity was twenty percent. Few of the guinea pigs developed flu as the temperature increased.

　 The virus stopped spreading completely at thirty degrees Celsius and eighty percent humidity. The researchers also found that the animals spread the virus among themselves nearly two days longer when the temperature was low.

　 One of the researchers said the study shows that flu virus is more likely to infect people during an outdoor walk on a cold day than in a warm room. He said cold air helps the virus survive in the air and low humidity helps it stay there longer. That is because particles of the virus ride on the extremely small drops of water floating in the air. When the air is very humid, water droplets fall to the ground more quickly.

　 The researchers say, however, that people should not stay in warm places all the time in cold weather to avoid the flu. They say the best way to prevent the sickness is to get yearly injections of a vaccine that prevents flu.

1. From the passage we can conclude that ________.

A. flu sometimes is deadly to weak people

B. flu virus can be killed by the warm weather

C. flu virus can be killed by the low humidity

D. animals get infected with flu easier than human beings

2. According to the passage, why is a person infected with the flu easily in winter?

A. Because in winter people tend to stay in the warm room.

B. Because in winter some people stay outdoor for long.

C. Because flu virus survive longer in cold and dry weather.

D. Because people are weaker in winter.

3. Which of the following words can replace the underlined word in the first paragraph?

A. Exposes. B. Breathes.

C. Frees. 　　　 D. Faces.

4. Which of the following will probably be discussed next?

A. How many kinds of flu have been identified.

B. How bird flu affected human being.

C. How the government controlled the flu.

D. How much the vaccine will cost.