tologists r***mmend avoiding the sun when it is most in tense?between 11 ?a.m.? and 3 p.m. Anyone who insists on sunbathing should use a g ood sun screen. These lotions and salves contain chemicals, such as para-aminobe nzoic acid, that block out the burning UV-B radiation while permitting the tanni ng rays to reach the skin.
1According to the passage, overexposure to the sun may result in____
2The word /!deity" in the s***nd paragraph refers to_____
24、 同上篇
1Which of the following comes first as a possible damage by UV radiation?____
2Why does the repair process of the DNA may finally fail?____
3The last paragraph of the passage mainly discusses____
25、 Smoking and Cancer Americans smoke six thousands million cigarettes every year (1970 figures). This is roughly the equivalent of 4195 cigarettes a year for every person in the country of 18 years of age or more. It is estimated that 51 % of American men s moke compared with 34 % of American women. Since 1939, numerous scientific studies have been conducted to determine whe ther smoking is a health hazard. The trend of the evidence has been consistent a nd 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 a shortened life expectancy. Cigarette smoking is believed by most research workers in this field to be a n important factor in the development of cancer of the lungs and cancer of the t hroat. Male cigarette smokers have a higher death rate from heart disease than O n-smoking males. Female smokers are thought to be less affected because they do not breathe in the smoke so deeply. The majority of physicians and researchers consider these relationships proved to their satisfaction and say, ’Give up smoking! If you don’t smoke, don’t start! ’ . It might be helpful to look at what tobacco-smoking actually does to the hum an body. Smoke is a mixture of gases, vaporized chemicals, minute particles of a sh, and other solids. There is also nicotine, which is a powerful poison, and bl ack tar. As the smoke is breathed in, all these components form deposits on the membranes of the lungs. One point of concentration of deposits is where the air tube divides. Most lung cancer begins at this point. Smoking also affects the heart and blood vessels. It is known to be related to Beurger’s disease, a narrowing of the small veins in the hands and feet that can cause great pain. Smokers also die much more often from heart disease. While all tobacco-smoking affects life expectancy and health, cigarette smok ing appears to have a much greater effect than cigar or pipe smoking. However, n icotine consumption is not diminished by the latter forms, and current research indicates a causal relationship between all forms of smoking and cancer of the m outh 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.
1Which of the following statements is NOT true according to the info rmation given in the passage? ____
2The statement "be associated with a shortened life expectancy" in the s***nd aragraph signifies____
3Female smokers are probably less affected by heart disease because____
4Tobacco smoke is a mixture____
5Harmfulness from all forms of smoking to the human body may be arranged in severity sequence as follows:____
考试问吧
