【正确答案】 A

【答案解析】[听力原文]
Until the twentieth century cigarettes were not an important threat to public health. Men used tobacco mainly in the form of cigars, chewing tobacco, and pipe tobacco. Most women did not use tobacco at all.
The cigarette industry began in the 1870s with the development of cigarette manufacturing machine. This made it possible to produce great numbers of cigarettes very quickly and it reduced price. Today cigarette smoking is a widespread habit. About forty-three percent of the men and thirty-one percent of adult women in the United States smoke cigarettes regularly. Men as a group smoke more than women. Among both men and women the age with the highest proportion of smokers is the age group 24-44.
Income, education, and occupation all play a part in determining a person"s smoking habits. City people smoke more than people living on farms. Well-educated men with high income are less likely to smoke cigarettes than men with fewer years of schooling and lower incomes. On the other hand, if a well-educated man with a high income smokes at all, he is likely to smoke more packs of cigarettes per day.

Why cigarettes were not an important threat to public health before the twentieth century?

【正确答案】 C

【答案解析】[听力原文]
What serves as a trigger to the cigarette industry?

【正确答案】 D

【答案解析】[听力原文]
What element is not decisive in taking up cigarette smoking?

【正确答案】 B

【答案解析】[听力原文]
Who tends to be heavy-smoker?