职称英语理工类阅读理解中英文对照精选练习题(9)

　　1. Americans smoke six thousand million cigarettes every year . This is roughly the equivalent of 4,195 cigarettes a year for every person in the country of 18 years of age or more. It is estimated that 51% of American men smoke compared with 34% of American women. 　　2. Since 1939, numerous scientific 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, particularly cigarette smoking, is associated with shortened life expectancy. 　　3. 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 the bladder and the oral cavity. Male cigarette Smokers have a higher death rate from heart disease than non-smoking males. The majority of doctors and researchers consider these relationships proved to their satisfaction and say, Give up smoking. If you dont smokedont start! 　　4. Some competent physicians and research workersthough their small number is decreased even furtherare less sure of the effect of cigarette smoking on health. They consider the increase in respiratory diseases and various forms of cancer may possibly be explained by other factors in the complex human environment atmospheric pollution, increased nervous stress, chemical substances in processed food, or chemical pesticides that are now being used by farmers in vast quantities to destroy insects and small animals. Smokers who develop cancer or lung diseases, they say, may also, by coincidence, live in industrial areas, or eat more canned food. Gradually, however, research is isolating all other possible factors and proving them to be statistically irrelevant. 　　5. Apart from the scientific statistics, it might be helpful to look at what smoking tobacco actually 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 a powerful poison, and black tar. As the smoke is breathed in, all these components form deposits on the membranes of the lungs. One point of concentration is where the air tube, or bronchus, divides. Most lung cancer begins at this point. 　　6. Smoking also affects the heart and blood vessels. It is known to be related to Beurgers disease, a narrowing of the small veins in the hands and feet that can cause great pain and lead even to amputation of limbs. Smokers also die much more often from heart disease. 　　7. While all tobacco smoking affects life and expectancy and health, cigarette smoking appears to have a much greater effect than cigar or pipe smoking. However, nicotine consumption is not diminished by the latter forms, and current research indicates a causal relationship between all forms of smoking and cancer of the mouth and throat. Filters and low tar tobacco are claimed to make smoking to some extent safer, but they can only marginally reduce, not eliminate the hazards.