单选题 Air pollution triggers more heart attacks than using cocaine and poses as high a risk of sparking a heart attack as alcohol, coffee and physical exertion. The findings, published in The Lancet journal, suggest population-wide【C1】______like polluted air should be【C2】______more seriously when looking at heart risks, and should be put into context beside higher but relatively【C3】______risks like drug use. Researchers combined data【C4】______36 separate studies and calculated the relative risk【C5】______by a series of heart attack triggers. They found that of the triggers for heart attack studied, cocaine is the most【C6】______to trigger an event in an individual,【C7】______traffic has the greatest population effect as more people are【C8】______to it. A report published late last year found that air pollution in many major cities in Asia【C9】______the WHO's air quality guidelines and that toxic cocktails of pollutants【C10】______more than 530,000 premature deaths a year. While【C11】______smoking was not included in this study, the researchers said the effects of second-hand smoke were likely to be【C12】______to that of outdoor air pollution, and noted previous research which found that bans on smoking in public places have significantly【C13】______heart attack rates. British researchers said last year that a ban on smoking in public places in England【C14】______to a swift and significant drop in the number of heart attacks,【C15】______the health service 8.4 million pounds in the first year. 【C16】______, what triggers the heart attack should be considered the "last straw." The【C17】______of heart disease that lead to a heart attack are【C18】______down over many years. If someone wants to【C19】______a heart attack they should focus on not smoking, exercising, eating a healthy diet and【C20】______their ideal weight.

【正确答案】 B

【答案解析】解析：形容词辨析题。此空位于副词relatively和名词risks之间，而根据空格前的but一词，可推知此处需填入与前面的higher语义相反的形容词比较级。空格后举了drug use为例，由此推断填入的形容词应能体现drug use的特点，即风险高但______，B项scarcer“更稀少”填入此空，意为“受害人群相对较小”，符合语义。

【正确答案】 A

【答案解析】解析：上下文语义题。该空后接一个完整的句子，故可知应填连接词，连接前一句一起表示研究的发现。空格前表示“就个体而言，吸食可卡因最______致病”，空格后则表明“交通拥堵对人群的影响力最大”，前后之间是“个体”和“群体”的对比，语义上有转折，故选A项but。

【正确答案】 B

【答案解析】解析：动词辨析题。文章主要讲述空气污染更容易诱发心脏病，故可推知此处也是表示负面语义。该空作that从句的谓语，这里从句主语“亚洲许多主要大城市的空气污染指数”应该是超过“世界卫生组织制定的空气质量标准”。exceeds“超过”符合语义，故选B项。

【正确答案】 C

【答案解析】解析：固定搭配题。此处将二手烟的影响与户外空气污染的影响联系起来。上一段末句提到研究报告指出了空气污染造成的影响，这里则承接上文以表转折的while引出二手烟的影响。根据“虽然此项研究并没有包括吸烟”和the effect of second-hand smoke，推断此处想表达“二手烟的影响”与“户外空气污染的影响”存在相似性，故选C项be similar to“相似”。