职称英语（卫生类）模拟试题（一）
Fortunately, most of these cancers are highly curable. But they can be disfiguring and take time to treat. For that reason, sun worshippers should treat deity with a good deal of awe. Sunburn, of course, is the initial hazard posed by UV radiation. Prolonged exposure to UV, however, interferes with the production of collagen fibers in the dermis, causing the skin to lose elasticity and creating premature wrinkles. Further deterioration of the dermis deprives the epidermis of nutrition and causes it to become thin and dry.
Cancer is UV's final result. Shortwave radiant energy, especially from the UV-B band, breaks the strands of DNA. Enzymes work constantly to rearrange the DNA into proper sequence, but with repeated UV exposure, the repair process may eventually break down. Then the mutant DNA may produce a colony of cancer cells. But skin cancer may be avoided with a good dose of common sense. People with fair skin and blue eyes who burn easily stand the highest risk. Special danger spots are the parts of the body most constantly exposed to the sun, such as the cheeks, nose, lower lip and the ears. People who have already developed precancerous lesions or had one skin-cancer growth stand a greatly increased chance of developing others.
Dermatologists recommend avoiding the sun when it is most intense between 11 a.m. and 3 p.m. Anyone who insists on sunbathing should use a good sun screen. These lotions and salves contain chemicals that block out the burning UVB radiation while permitting the tanning rays to reach the skin.
31. According to the passage, over-exposure to the sun may result in ______
A. the wrinkles that cannot be seen.
B. the skin cancer.
C. all kinds of sacrifices.
D. healthful beauty.
32. The underlined word “deity” in the third paragraph refers to ________
A. something mysterious.
B. the skin cancer.
C. the sun.
D. overexposure to the sun.
33. Which of the following comes first as a possible damage by UV radiation?
A. Sunburn.
B. The loss of skin elasticity.
C. Dryness of epidermis.
D. The deterioration of dermis.
34. Why may the repair process of the DNA finally fail?
A. Because shortwave radiant energy breaks the strands of the DNA.
B. Because the DNA may produce a colony of cancer cells.
C. Because enzymes work to rearrange the DNA into a new order.
D. Because the patient is exposed to UV from time to time.
35. The last paragraph of the passage mainly discusses________
A. the treatment of the skin cancer.
B. the prevention of the skin cancer.
C. the parts of the body where cancer is most likely to develop.
D. the lotions that work best in fighting against the skin cancer.
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Population Densities
The average population density of the world is 47 persons per square mile. Continental densities range from no permanent inhabitants in Antarctica to 211 per square mile in Europe. In the western hemisphere, population densities range from about 4 per square mile in Canada to 675 per square mile in Puerto Rico. In Europe the range is from 4 per square mile in Iceland to 831 per square mile in the Netherlands.
Within countries there are wide variations of population densities. For example, in Egypt, the average is 55 persons per square mile, but 1,300 person inhabit each square mile in settled portions where the land is arable.
High population densities generally occur in regions of developed industrialization, such as the Netherlands, Belgium, and Great Britain, or where lands are intensively used for agriculture, as in Puerto Rico and Java. Low average population densities are characteristic of most underdeveloped countries.
Low density of population is generally associated with a relatively low percentage of cultivated land. This generally results from poor quality lands. It may also be due to natural obstacles to cultivation, such as deserts, mountains, or malaria-infested jungles; to land uses other than cultivation, as pasture and forested land; to primitive methods that limit cultivation; to social obstacles.
More economically advanced countries of low population density have, as a rule, large proportions of their populations living in urban areas. Their rural population densities are usually very low. Poorly developed countries of correspondingly low population density, on the other hand, often have a concentration of rural population living on arable land, which is as great as the rural concentration found in the most densely populated industrial countries.
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