Half of the world’s population is affect

题目：

     Half of the world’s population is affected by Asian monsoons（季风）, but monsoons are difficult to

predict. American researchers have put together a 700-year record of the rainy seasons, which is

expected to provide guidance for experts making weather predictions.

     Every year, moist （潮湿的）air masses, known as monsoon，produce large amounts of rainfall in

India, East Asia, Northern Australia and East Africa. All this wet air is pulled in by a high pressure area

over the Indian Ocean and a low pressure area to the south.

     According to Edward Cook, a weather expert at Columbia University in New York, the complex

nature of the climate systems across Asia makes monsoons hard to predict. In addition, climate records

for the area are too recent and not detailed enough to be of much use. Therefore, he and a team of

researchers spent more than fifteen years traveling across Asia, looking for trees old enough to provide

long-term records. They measured the rings, or circles, inside thousands of ancient trees in more than 300 places.

     Rainfall has a direct link to the growth and width of rings on some kinds of trees. The researchers

developed a document they are calling a Monsoon Asia Drought Atlas. It shows the effect of monsoons

over seven centuries, beginning in the 1300s.

     Professor Cook says the tree-ring records show periods of wet and dry weather. "If the monsoon

basically fails or is a very weak one, the trees affected by monsoons at that location might put on a very

narrow ring. But if the monsoon is very strong, the trees affected by that monsoon might put on a wide

ring for that year. So, the wide and narrow ring widths of the chronology that we developed in Asia

provide us with a measure of monsoon variability." With all this information, researchers say they can

begin to improve computer climate models for predicting the behavior of monsoons.

     "There has been widespread famine and starvation and human dying in the past in large droughts. And

on the other hand, if the monsoon is particularly heavy, it can cause extensive flooding." said Eugene

Wahl, a scientist with America's National Oceanic and Atmospheric Administration. "So, to get a sense

of what the regional moisture patterns have been, dryness and wetness over such a long period of time in

great detail, I would call it a kind of victory for climate science."

1. What'sthe passage mainly about?

A. The effects of Asian monsoons.            

B. The necessity of weather forecast.

C. The achievements of Edward cook.        

D. A breakthrough in monsoon prediction.

2. It is difficult for experts to predict Asian monsoons because_________

A. it is hard to keep long-term climate records.  

B. they are formed under complex climate systems.

C. they influence many nations.              

D. there is heavy rainfall in Asia.

3. What can be inferred from the passage?

A. Long and details climate records can offer useful information for monsoon research.

B. The Monsoon Asia Drought Atlas has a monsoon record for about 1,300 years.

C. The trees affected by monsoon grow fast if the monsoon is weak.

D. The rainfall might be low although the monsoon is strong in monsoon-affected areas.

4. What do we know about the research according to Eugene Wahl?

A. It is a great achievement in climate science.

B. It should include information about human life in the past.

C. It has analysed moisture models world wide,

D. It will help people prevent droughts and floods.

5. Which of the following best describes the tone of this passage?

A. Matter-of-fact    

B. Pessimistic    

C. Humorous    

D. Friendly.