问题 选择题

读下面“地质构造或地貌景观图”,回答题。

小题1:图示中主要由内力作用形成的是(  )

A.①④

B.②③

C.①③

D.②④小题2:图示中由内外力共同作用形成的是 (  )

A.①②

B.①②③

C.①③④

D.①②③④

答案

小题1:A

小题2:A

题目分析:有示意图可知:①为褶皱,为地壳的水平运动使岩层弯曲变形而成,属于内力作用,②为风蚀蘑菇,为风力侵蚀作用形成的,属于外力作用,③为流水沉积形成的河口三角洲,也为外力作用,④为断层,成因为地壳运动产生的强大压力或张力,超过了岩层所能承受的强度,岩层发生断裂,并沿断裂面发生明显的位移,形成的,属于内力作用。

点评:结合景观图获取信息是解答问题的关键。有外力作用形成的地貌有风蚀蘑菇、沙丘、黄土高原千沟万壑的地表、瀑布、峡谷、冲积扇、冲积平原、三角洲等,有内力作用形成的地貌有褶皱、断层等。

单项选择题
问答题

Exactly where we will stand in the long war against disease by the year 2050 is impossible to say. (46) But if developments in research maintain their current pace, it seems likely that a combination of improved attention to dietary and environmental factors, along with advances in gene therapy and protein targeted drugs, will have virtually eliminated most major classes of disease.

From an economic standpoint, the best news may be that these accomplishments .could be accompanied by a drop in health-care costs. (47) Costs may even fall as diseases ’are brought under control using pinpointed, short-term therapies now being developed. By 2050 there will be fewer hospitals, and surgical procedures will be largely restricted to the treatment of accidents and other forms of trauma. Spending on nonacute care, both in nursing facilities and in homes, will also fall sharply as more elderly people lead healthy lives until close to death.

One result of medicine’s success in controlling disease will be a dramatic increase in life expectancy. (48) The extent of that increase is a highly speculative matter, but it is worth noting that medical science has already helped to make the very old (currently defined as those over 85 years of age) the fastest growing segment of the population. Between 1960 and 1995, the U.S. population as a whole increased by about 45%, while the segment over 85 years of age grew by almost 300%. (49) There has been a similar explosion in the population of centenarians, with the result that survival to the age of 100 is no longer the newsworthy feat that it was only a few decades ago. U.S. Census Bureau projections already forecast dramatic increase in the number of centenarians in the next 50 years: 4 million in 2050, compared with 37, 000 in 1990.

(50) Although Census Bureau calculations project an increase in average life span of only eight years by the year 2050, some experts believe that the human life span should not begin to encounter any theoretical natural limits before 120. years. With continuing

(47) Costs may even fall as diseases ’are brought under control using pinpointed, short-term therapies now being developed.