第23题: [单项选择]What does the passage say about the secondhand smoke A. It threatens public health. B. It gets more serious in the United States. C. It is more dangerous than AIDS. D. It is a topic of public debat 参考答案:A 答案解析:[解析] 根据“二手烟是严重威胁公众健康的因素之一(...secondhand tobacco smoke is a serious public health risk.)。”可知答案为A。