　　Since 1939, numerous studies have been conducted to determine whether smoking is a health hazard. The trend of the evidence has been consistent and indicates that there is a serious health risk. Research teams have conducted studies that show beyond all reasonable doubt that tobacco smoking is associated with a shortened life expectancy1.

　　Cigarette smoking is believed by most research workers in this field to be an important factor in the development of cancer of the lungs and cancer of the throat and is believed to be related to cancer of some other organs of the body. Male cigarette smokers have a higher death rate from heart disease than non-smoking males. Female smokers are thought to be less affected because they do not breathe in the smoke so deeply.

　　Apart from statistics, it might be helpful to look at what smoking tobacco does to the human body. Smoke is a mixture of gases, vaporized chemicals, minute particles of ash and other solids. There is also nicotine, which is powerful poison, and black tar. As smoke is breathed in, all those components form deposits on the membranes of the lungs. One point of concentration is where the air tube and bronchus divides. Most lung cancer begins at this point.

　　Filters and low tar tobacco2 are claimed to make smoking to some extent safer, but they can only slightly reduce, not eliminate the hazards.

　　词汇：

　　vaporize /5veIpEraIz/ v. (使)蒸发 nicotine /5nikEti:n/ n.尼古丁 membrane /5membrein/ n.膜 bronchus /5brCNkEs/ n.支气管filter /5filtE/ n.过滤嘴注释：

　　1. life expectancy：预期寿命

　　2. low tar tobacco：焦油含量低的烟草练习：

　　1. It is easy to determine whether smoking is hazardous. A Right B Wrong C Not mentioned

　　2. Smoking reduces one’s life expectancy. A Right B Wrong C Not mentioned

　　3. Smoking may induce lung cancer. A Right B Wrong C Not mentioned

　　4. There is evidence that smoking is responsible for breast cancer. A Right B Wrong C Not mentioned

　　5. Male smokers have a lower death rate from heart disease than female smokers. A Right B Wrong C Not mentioned

　　6. Nicotine is poisonous. A Right B Wrong C Not mentioned

　　7. Filters and low tar tobacco make smoking safe. A Right B Wrong C Not mentioned

　　答案与题解：

　　1. B 该题说的是：判断抽烟对健康是否有危害是容易的。但是，文章的第一句话是这么说的：自 1939年以来，进行了许多次研究，其目的都是为了判断抽烟对健康是否是一种危害。可以看出判断抽烟对健康是否是一种危害并不容易。

　　2. A 该题说的是：抽烟会缩短人们的预期寿命。该题源于第一段最后一个句子中的子句： tobacco smoking is associated with a shortened life expectancy抽烟会缩短人们的预期寿命。

　　3. A 该题说的是：抽烟有可能诱发肺癌，文章的第二段和第三段都讲到了抽烟与肺癌的关系。

　　4. C该题说的是：有证据说明乳腺癌是抽烟诱发的。文章没有提及乳腺癌与抽烟的关系。

　　5. B 该题说的是：男性烟民死于心脏病的比率小子女性烟民死于心脏病的比率。文章没有直接比较男性烟民和女性烟民死于心脏病的比率，但有这么一句话： Female smokers are thought to be less affected because they do not breathe in the smoke so deeply.据认为女性烟民并不把烟吸得很深，烟对她们的影响小子男性烟民。从中可以推断出的是：男性烟民死于心脏病的比率高于女性烟民死子心脏病的比率。因此该题的命题是错误的。

　　6. A 该题说的是：尼古丁是有毒的。答案可在第三段找到。

　　7. B 该题说的是：有了过滤嘴和焦油含量低的烟草，抽烟是安全的。文章的最后一段(也是最后一句 )是这么说的：据称，过滤嘴和焦油含量低的烟草在某种程度上使抽烟变得较为安全，但是它们只是略微减少危害而不是消除危害。因此该题的命题是错误的。