A new study finds that such renewable energy might be green in another sense. Large collections of those turbines or solar panels appear capable of bringing rains to the desert and would allow more plants to grow. Building large wind or solar farms just to study their question was not an option. It would be too costly. So experts Kalnay and Safa developed a model of North Africa's Sahara Desert to find out how wind turbines and solar farms might alter the desert's climate. The team ran its model several times. In one run，it assumed that people would set up wind farms only. Another run assumed people would install just solar farms. A third assumed people would build both. They would affect the desert's weather with temperature and average daily rain increased-but differently. Installing a mix of solar farms and wind turbines brought about a bigger change-not in temperature but in rainfall. In the Sahara，having both wind and solar farms more than doubled the amount of rain that fell，up to 215.4 millimeters per day. The models predicted that the average rainfall would increase over time，as more plants grew. Plants move water from the ground to the air. Warmer air can carry more water. So as this air rises，it can ferry more water up to become clouds. Those clouds can release rain，relieving the thirst of plants below. Over time， this process repeats itself over and over. This positive feedback can greatly boost rains. Such rainfall changes could lead to better agriculture，says Safa. "More rain also would help wild plants grow. We believe that the countries in the Sahara should seriously consider investing in wind and solar power"，he added.（1）What is the new finding of the research？ ____

Wind turbines（涡轮）and solar panels that generate electricity are examples of "green" technology. A new study finds that such renewable energy might be green in another sense. Large collections of those turbines or solar panels appear capable of bringing rains to the desert and would allow more plants to grow.
    Building large wind or solar farms just to study their question was not an option. It would be too costly. So experts Kalnay and Safa developed a model of North Africa's Sahara Desert to find out how wind turbines and solar farms might alter the desert's climate.
    The team ran its model several times. In one run，it assumed that people would set up wind farms only. Another run assumed people would install just solar farms. A third assumed people would build both. They would affect the desert's weather with temperature and average daily rain increased-but differently. Installing a mix of solar farms and wind turbines brought about a bigger change-not in temperature but in rainfall. In the Sahara，having both wind and solar farms more than doubled the amount of rain that fell，up to 215.4 millimeters per day.
    The models predicted that the average rainfall would increase over time，as more plants grew. Plants move water from the ground to the air. Warmer air can carry more water. So as this air rises，it can ferry more water up to become clouds. Those clouds can release rain，relieving the thirst of plants below. Over time， this process repeats itself over and over. This positive feedback can greatly boost rains.
    Such rainfall changes could lead to better agriculture，says Safa. "More rain also would help wild plants grow. We believe that the countries in the Sahara should seriously consider investing in wind and solar power"，he added.
（1）What is the new finding of the research？ ____
A. Deserts will be suitable for farming.
B. It costs much to get deserts greener.
C. Renewable energy can green a desert.
D. Clean energy helps plants grow better.
（2）What discouraged experts from building energy farms？ ____
A. High construction expenses.
B. A lack of suitable test sites.
C. Shortage of manpower.
D. Terrible climate.
（3）What was the advantage of the third run？ ____
A. Saving more energy with less cost.
B. Doubling global rainfall per year.
C. Raising daily rainfall in the desert.
D. Decreasing temperature in the desert.
（4）What may Safa advise the countries in the Sahara to do？ ____
A. Build more farms to grow crops.
B. Save more water for agriculture.
C. Invest in wind and solar power.
D. Consider moving to other places.