These days we hear a lot about how air pollution is changing temperatures on the earth. New evidence from a mountaintop in China now suggests that pollution can also change the amount of rain and snow that falls in some places.
Usually, more rain falls in mountainous places than in flat areas upwind from the mountains. That’s because air can hold a lot of water. When wind blows wet air up a mountainside, the air gets colder. This temperature change often forces water to fall as rain or snow.
In recent years, however, many mountainous areas in the western United States have been getting less rain than normal. Mountains that are downwind from cities have experienced the biggest drops.
Some scientists have theorized（推理）that pollution drifts （趋势）from the cities into the mountains, affecting rainfall, but proving this link has been difficult.
Searching for answers, a team led by a scientist from the Hebrew University went to s mountain in China called Mount Hua, which is 2,060 meters tall and lies about 120 kilometers east of the Chinese city Xi’an. Since 1954, scientists have been collecting details about rainfall, humidity（湿度）, and visibility（能见度）in the area.
Using this data, the scientists pared rainfall on Mount Hua to rainfall in the nearest city, Huayin, on days with different levels of visibility. When the air was clear and people could see as far as 20 km, the scientists found that 65% more rain fell on the mountain than in the city.
But when the air was smoggy, allowing only 8 km of visibility through the mist, the mountain received just 20% more rain than the city. The new data supports the theory that pollution affects rainfall.
Some scientists believe that there are other explanations for the numbers. It’s possible, for example, that natural particles（微粒）in the air, rather than particles produced by pollution, are affecting visibility.
【小题1】According to the 1st paragraph, air pollution is changing the following EXCEPT .A．the temperature B．the amount of rain C．the habit of eatingD．the amount of snow【小题2】According to the passage, what will probably happen when the wet air in the sky gets colder?A．It will probably rain or snowB．It will probably be cloudy.C．It will probably windD．It will probably bee dry.【小题3】Why did the team led by a scientist go to Mount Hua?A．They wanted to pay a visit to Mount Hua.B．They wanted to collect the data for their theory.C．They wanted to measure Mount Hua.D．They wanted to have a good rest on Mount Hua.【小题4】You can most probably read the passage in .A．a travel guideB．a telephone bookC．a cartoon bookD．a science bookC
网友回答
(答案→)C
解析：
【小题1】从第一段提供的信息可知，air pollution正在改变全球temperature、the amount of rain and snow。所以选项Ｃ是正确答案。）
【小题2】从第二段中的句子“When wind blows wet air up a mountainside, the air gets colder. This temperature change often forces water to fall as rain or snow.”可知，A是正确答案。）
【小题3】从第五段提供的信息可知，B是正确答案。）
【小题4】本文讲述的是科学家们的研究结果，所以最有可能出现在a science book里。）