A-A+
The relationship between exposure to ______has
问题详情
The relationship between exposure to ______has not yet been determined.
A．ozone and fall in lung function
B．ozone and lung diseases such as asthma
C．nitrogen dioxide and worse lung function
D．smog and chronic bronchitis and emphysema
参考答案
正确答案：D
解析：文章第三段最后一句话“It is suspected that long-term exposure to smog may result in chronic bronchitis and emphysema，but this has yet to be proven．”说明这些疾病和烟雾之间的关系还有待验证。故选D项。
