unit21 Lesson 2同步训练 北师大版选修7.docVIP

第二部分 阅读理解 阅读下面短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。 Housework might be bad for your health, according to a study suggesting that tidying up as little as once a week with common cleaning sprays and air fresheners could raise the risk of asthma (哮喘) in adults. Other studies have linked these types of products with increased asthma rates among cleaning professionals but the research published recently indicates others are potentially at risk as well. Exposure (暴露) to such cleaning materials even just once a week could account for as many as one in seven adult asthma cases, the researchers wrote in an American medicine magazine. Asthma is an inflammation (炎症) of the airways with symptoms that include wheezing (喘息), shortness of breath, coughing and chest tightness. More than 300 million people worldwide suffer from the condition. Using data collected from 22 centers in 10 European countries, the researchers studied about 3,500 people over a nine-year period to see how many developed asthma and whether cleaning could be a cause. Two-thirds of those in the study who reported doing the large part of cleaning were women and fewer than 10 percent of them were full-time homemakers. the study found that the risk of developing asthma increased with the frequency (频率) of cleaning and the number of different sprays used but on average was about 30 to 50 percent higher in people exposed to cleaning sprays at least once a week. While air fresheners, furniture cleaners and glass cleaners had the strongest effect, the researchers said the study did not determine what caused the increase. 1. the underlined word “potentially” in the second paragraph probably means “_______”. A. seriously, but not deadly B. not actually, but likely C. certainly to happen D. obviously to see 2. According to researchers, about _______ of adult asthma cases are caused by cleaning sprays and air fresheners. A. 1% B. 15% C. 30% D. 50% 3. Which of the following is NOT a symptom of a