1、托福-练习二十九及答案解析(总分：26.00，做题时间：90 分钟)一、BPassage 1/B(总题数：2，分数：4.00)1. LIFE EXPECTANCY1 The greatest demographic story of the twentieth century was the enormous increase in life expectancy, the average number of years a person can expect to live. In most modern societies, life expectancy rose dramaticall
2、y, from about 47 years in 1900 to about 76 years in 2000. This does not mean, however, that people suddenly died on their forty- seventh birthday in 1900. It means that if half of the people born in 1900 died in childhood and the rest lived 95 years, the average age at death was around 47. The data
3、for 1900 reflect high infant and childhood mortality rates. At that time, surviving the first fifteen years of life was the key to living to old age. Over the century, several factors increased life expectancy, most notably improvements in public health, such as pasteurized milk, sewers, and indoor
4、plumbing. Advances in medical practice, including the use of antibiotics and vaccinations for childhood illnesses, made it increasingly likely that infants would reach adulthood.2 On the one hand, increased life expectancy is a sign of societal well being; on the other hand, an aging population pose
5、s its own set of problems. Large numbers of elderly, many with chronic diseases, become a burden on the health care system and on their families. In societies where care of the elderly is a family responsibility, adult children caring for aging parents experience great personal and financial stress.
6、1. An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the pass
7、age or are minor ideas in the passage. This question is worth 2 points.* A. Around half of the population died on their forty-seventh birthday in 1900. B. The average number of years a person could expect to live rose from 47 to 76 in only a century. C. The leading causes of death in 1900 were epide
8、mic diseases. D. Mortality rate is the number of deaths in a period as a proportion of the entire population. E. Improvements in public health and medical practices significantly raised life expectancy. F. An aging population increases the stress on a societys health care system and on families.ABCD
9、EFBEFKey information: .life expectancy, the average number of years a person can expect to live, rose dramatically, from about 47years in 1900 to about 76years in 2000; .several factors increased life expectancy, most notably improvements in public health.Advances in medical practice.; Large numbers
10、 of elderly, many with chronic diseases, become a burden on the health care system and on their families. Answer (A) is inaccurate; answers (C) and (D) are not mentioned. （分数：2.00）(1). LIFE EXPECTANCY1 The greatest demographic story of the twentieth century was the enormous increase in life expectan
11、cy, the average number of years a person can expect to live. In most modern societies, life expectancy rose dramatically, from about 47 years in 1900 to about 76 years in 2000. This does not mean, however, that people suddenly died on their forty- seventh birthday in 1900. It means that if half of t
12、he people born in 1900 died in childhood and the rest lived 95 years, the average age at death was around 47. The data for 1900 reflect high infant and childhood mortality rates. At that time, surviving the first fifteen years of life was the key to living to old age. Over the century, several facto
13、rs increased life expectancy, most notably improvements in public health, such as pasteurized milk, sewers, and indoor plumbing. Advances in medical practice, including the use of antibiotics and vaccinations for childhood illnesses, made it increasingly likely that infants would reach adulthood.2 O
14、n the one hand, increased life expectancy is a sign of societal well being; on the other hand, an aging population poses its own set of problems. Large numbers of elderly, many with chronic diseases, become a burden on the health care system and on their families. In societies where care of the elde
15、rly is a family responsibility, adult children caring for aging parents experience great personal and financial stress.1. An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in
16、 the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.（分数：1.00）A.B.C.D.E.F.(2). ARTISTS USE OF OIL AND ACRYLIC PAINTS1 The oil technique for painting on canvas is s
17、uperior to other methods mainly because of its great flexibility and ease of manipulation, as well as the wide range of effects that can be produced. Colors do not change to any great extent on drying, which means that the color the artist puts down is, with only slight variation, the color desired
18、in the finished work. The artist is free to combine transparent and opaque effects in the same painting. However, the principal defect of oil painting is the darkening of the oil over time, but this may be reduced by using the highest quality materials.2 The most widely used artists colors based on
19、the synthetic resins are made by dispersing pigment in acrylic emulsion. Acrylic paints are thinned with water, but when they dry, the resin particles coalesce to form a tough film that is impervious to water. Acrylic colors may be made mat or glossy and can imitate most of the effects of other wate
20、r-based colors. They are a boon to painters with a high rate of production because a painting can be completed in one session that might have taken days in oil because of the drying time required between layers of paint.3 Acrylic colors are not a complete substitute for oil paints, and artists whose
21、 styles require the special manipulative properties of oil colors-including delicacy in handling or smoothly blended tones-find that these possibilities are the exclusive properties of oils. Although painting in acrylics has certain advantages over painting in oils, the latter remains the standard b
22、ecause the majority of painters find that its advantages outweigh its defects and that in optical quality oil paints surpass all others.2. Select the appropriate sentences from the answer choices and match them to the type of paint that they describe. TWO of the answer choices will NOT be used. This
23、 question is worth 3 points.Answer ChoicesA. They appear transparent on paper.B. The colors can be thinned with water.C. They allow for smoothly blended tones.D. The paints are applied to wet plaster.E. They are the preferred paints among artists.F. They have a relatively fast drying time.G. The col
24、ors will eventually darken.（分数：1.00）A.B.C.D.E.F.G.WORLD CLIMATIC PATTERNS1 Climate is the general pattern of atmospheric conditions, seasonal variations, and weather extremes in a region over a period of decades. One major factor determining the uneven patterns of world climates is the variation in
25、the amount of solar energy striking different parts of the earth. The amount of incoming solar energy reaching the earths surface varies with latitude, the distance north or south from the equator. Air in the troposphere is heated more at the equator (zero latitude), where the sun is almost directly
26、 overhead, than at the high-latitude poles, where the sun is lower in the sky and strikes the earth at a low angle.2 The large input of heat at and near the equator warms large masses of air. These warm masses rise and spread northward and southward, carrying heat from the equator toward the poles.
27、At the poles, the warm air becomes cool and falls to the earth. These cool air masses then flow back toward the equator near ground level to fill the space left by rising warm air masses. This general air circulation pattern in the troposphere results in warm average temperatures near the equator, c
28、old average temperatures near the poles, and moderate average temperatures at the middle latitudes.3 The larger input of solar energy near the equator evaporates huge amounts of water from the earths surface into the troposphere. As the warm, humid air rises, it cools rapidly and loses most of its m
29、oisture as rain near the equator. The abundant rainfall and the constant warm temperatures near the equator create the worlds tropical rain forests.4 Two major factors cause seasonal changes in climate. One is the earths annual orbit around the sun; the other is the earths daily rotation around its
30、tilted axis, the imaginary line connecting the two poles. When the North Pole leans toward the sun, the suns rays strike the Northern Hemisphere more directly per unit of area, bringing summer to the northern half of the earth. At the same time, the South Pole is tilted away from the sun; thus, wint
31、er conditions prevail throughout the Southern Hemisphere. As the earth makes its annual rotation around the sun, these conditions shift and cause a change of seasons.5 As the earth spins around its axis, the general air circulation pattern between the equator and each pole breaks into three separate
32、 belts of moving air, or prevailing surface winds, which affect the distribution of precipitation over the earth.（分数：2.00）(1).Select the appropriate sentences from the answer choices and match them to the location that they describe. TWO of the answer choices will NOT be used. This question is worth
33、 3 points.Answer ChoicesA. Solar energy strikes the earth at a low angle.B. Average annual temperatures are moderate.C. The large input of solar energy heats great masses of air.D. A large quantity of water evaporates into the atmosphere.E. Warm air cools and sinks to the earths surface.F.The sun is
34、 almost directly overhead.G. There are three belts of prevailing surface winds.（分数：1.00）A.B.C.D.E.F.G.(2).An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. So
35、me sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.（分数：1.00）A.B.C.D.E.F.二、BPassage 2/B(总题数：2，分数：22.00)BLACK HOLES1 Nothing in the history of modern astronomy has excited as much
36、 speculation as the object, or event, known as a black hole. Black holes have provided endless imaginative Ufodder/U for science fiction writers and endless theoretical Ufodder/U for astrophysicists. They are one of the more exotic manifestations of the theory of general relativity, and their fascin
37、ation lies in the way their tremendous gravity affects nearby space and time.2 A black hole is very simple in structure: it has a surface-the event horizon-and a center-the singularity. Everything else is gravity. The standard model for the formation of a black hole involves the collapse of a large
38、star. The imaginary spherical surface surrounding the collapsed star is the event horizon-an artificial boundary in space that marks a point of no return. Outside the event horizon, gravity is strong but Ufinite/U, and it is possible for objects to break free of its pull. However, once within the ev
39、ent horizon, an object would need to travel faster than light to escape.（分数：11.00）(1).The word Ufodder/U in paragraph 1 is closest in meaning to A. material B. stories C. support D. problems（分数：1.00）A.B.C.D.(2).The word Ufinite/U in paragraph 2 is closest in meaning to A. increasing B. beautiful C.
40、mysterious D. limited（分数：1.00）A.B.C.D.(3).What happens to an object that falls within the event horizon of a black hole? A. The object changes shape until it is spherical. B. The object is pushed from the hole at the speed of light. C. The object cannot escape the black holes gravity. D. The object
41、explodes into particles that drift into space.（分数：1.00）A.B.C.D.(4).The opposing force between the molecular particles inside a star is called A. general relativity B. the exclusion principle C. infinite density D. the singularity（分数：1.00）A.B.C.D.(5).The word Urunaway/U in paragraph 3 is closest in m
42、eaning to A. frequent B. long-term C. uncontrolled D. slow-paced（分数：1.00）A.B.C.D.(6).Why does the author mention Ua cartoon character/U in paragraph 4? A. To illustrate the complete disappearance of a collapsing star B. To warn of the danger of being sucked into a black hole C. To point out a humoro
43、us phenomenon in astrophysics D. To announce the creation of a cartoon about black holes（分数：1.00）A.B.C.D.(7).Which sentence below best expresses the essential information in the highlighted sentence in paragraph 4? A. The collapse of a star creates a black hole, a distortion of space and time with g
44、ravity strong enough to pull in any nearby object. B. Several different kinds of black holes exist, but the most powerful are those that result in an interchange of space and time. C. Behind every black hole is a different type of hole that is even more disturbing to our current beliefs about gravit
45、y, space, and time. D. The process of black hole formation occurs only in regions of space where gravity is the predominant physical force.（分数：1.00）A.B.C.D.(8).Astronauts who fell into a black hole would probably experience all of the following EXCEPT A. distortion of and time space B. traveling fas
46、ter than light C. knowledge of the universe D. strong gravitational forces（分数：1.00）A.B.C.D.(9).What can be inferred from paragraph 6 about the distance between the event horizon and the singularity? A. The distance increases and decreases continuously. B. The distance is more than several trillion k
47、ilometers. C. The distance cannot be traveled in less than a year. D. The distance is related to the size of the black hole.（分数：1.00）A.B.C.D.(10).Look at the four squares, , , , and , which indicate where the following sentence could be added to the passage. Where would the sentence best fit?A few b
48、elieve that the astronauts would explode in a flash of gamma rays as they approached the singularity.What would happen to objects, such as astronauts, as they vanished into a black hole? Physicists have been amusing themselves with this question for years, and most believe that the intense gravitati
49、onal forces would rip apart the astronauts long before they were crushed at the singularity. Theoretically, any astronauts who managed to survive the passage would encounter some very strange things. For instance, they would experience acute time distortion, which would enable them to know, in a few brief seconds, the entire future of the universe. （分数：1.00）填空项 1:_(11).An introductory sentence for a brief
