C A new study shows that air pollution can cause a huge reduction in our intelligence. The study was a project involving researchers at Peking University in China and Yale University in the United States. The researchers reported that long-term exposure to air pollution can affect a person's mental abilities in two areas : Language and math. The researchers studied about 25,000 people from across China. Between 2010 and 2014, these Chinese men, women and children were given language and math tests. Then researchers compared the test results with measurements of pollution in the air, namely nitrogen dioxide and sulfur dioxide ( 二氧化硫 ) . Xi Chen of the Yale School of Public Health led the study. He and his team found that breathing polluted air can reduce a person's education level by about one year. Chen said that the effect generally is worse for those over 64 years of age, for men and for those with little or no education. “The older persons — they are more affected. And we find, quite amazingly, males are more affected than females. And people working outdoors are more affected than people working indoors. He noted that the youngest people in the study were 10 years old, while the oldest was 90 years old. They came from China's 33 provinces. In his words, the data and facts are convincing and this range of ages and locations across the country provided a real, objective and representative sample. The researchers noted that the effect of air pollution on verbal ability is even more serious as people age, especially among men and the less educated. The researchers also stressed that every country, whether developed, developing or poor, should focus on air pollution or humans will face a bad situation. 28. What is the result of the study? A. Air pollution has a bad effect on people's intelligence. B. Females are more affected by air pollution than males. C. Americans are more affected by air pollution than Chinese. D. People working indoors are actually not affected by air pollution. 29. What did Chen say about the study? A. It is doubtful. B. It is extremely unfair. C. It is common and not representative. D. It is relatively objective and persuasive. 30. What did the researchers emphasize in the last paragraph? A. The data from the 33 provinces is convincing. B. The whole world should pay attention to air pollution. C. The less educated take more responsibility for air pollution. D. Air pollution's influence on verbal ability is less serious as people age. 31. Where is the text most likely taken from? A. A life diary. B. A guidebook. C. A science magazine. D. A biography.