题目内容：

    About 4 million children worldwide develop asthma(哮喘) each year because of nitrogen dioxide(NO2 , 二氧化氮) air pollution, according to a study published by researchers at the George Washington University. The study estimates(估算) that 64 percent of these new cases of asthma occur in urban areas.

“The study is the first to quantify the worldwide burden of new pediatric(儿科的) asthma cases linked to traffic-related nitrogen dioxide by using a method that takes into account high exposure to this pollutant that occurs near busy roads, ” said Susan C. Anenberg, PhD, the senior author of the study.

“Our findings suggest that millions of new cases of pediatric asthma could be prevented in cities around the world by reducing air pollution,” said Anenberg. “Improving access to cleaner forms of transportation, like electrified public transport, cycling and walking, would not only bring down NO2 levels, but would also improve physical fitness, and cut greenhouse gas emissions(排放). ”

Asthma is a disease that makes it hard to breathe when the lung’s airways are swollen. An estimated 235 million people worldwide at present have asthma, which can cause life-threatening attacks.

The World Health Organization calls air pollution “a major environmental risk to health” and has offered Air Quality Guidelines for NO2 and other air pollutants. The researchers estimate that most children lived in areas below the NO2, guideline. They also found that about 92 percent of the new pediatric asthma cases that were caused by NO2 occurred in areas that already meet the WHO guideline.

“That finding suggests that the WHO guideline for NO2 may need to be re-evaluated to make sure it is conducive to the protection of children’s health,” said Pattanun Achakulwisut, PhD, lead author of the paper.

Additional research must be done to more persuasively identify what is leading to asthma within complex traffic emissions. This effort will help to improve the estimates of new asthma cases tied to traffic emissions.

1.What can we learn from Susan C. Anenberg?

A.Old forms of getting around need to be replaced.

B.Few cases of pediatric asthma occur in urban areas.

C.Pediatric asthma increases because of unclean energy.

D.Greener transportation helps to reduce asthma cases.

2.What can we infer about the Air Quality Guidelines for NO2?

A.It proved persuasive. B.It seemed unreasonable.

C.It would be abandoned. D.It turned out instructive.

3.What does the underlined word “conducive” in paragraph 6 probably mean?

A.Beneficial. B.Open.

C.Equal. D.Familiar.

4.What is the main idea of the text?

A.Asthma has put children’s life in unavoidable danger.

B.WHO should improve Air Quality Guidelines for NO2.

C.NO2 air pollution causes children to suffer from asthma.

D.Air pollution is a serious worldwide problem nowadays.