Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator.
To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one or at most a few species of insects or birds. Some orchids even change their scents to interest different insects at different times.
Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors. 【題組】
1. What does the passage mainly discuss?
10.【題組】10. Which of the following statements about orchids' scents does the passage support?
(A) They are effective only when an insect is near the blossom.
(B) Harmful insects are repelled by them.
(C) They are difficult to tell apart.
(D) They may change at different times.
One of the most important social developments that helped to make possible a shift in thinking about the role of public education was the effect of the baby boom of the 1950's and 1960's on the schools. In the 1920's, but especially in the Depression conditions of the 1930's, the United States experienced a declining birth rate-every thousand women aged fifteen to forty -four gave birth to about 118 live children in 1920, 89.2 in 1930, 75.8 in 1936, and 80 in 1940. With the growing prosperity brought on by the Second World War and the economic boom that followed it, young people married and established households earlier and began to raise larger families than had their predecessors during the Depression. Birth rates rose to 102 per thousand in 1946. 106.2 in 1950 and 118 in 1955. Although economics was probably the most important determinant, it is not the only explanation for the baby boom. The increased value placed on the idea of the family also helps to explain this rise in birth rates. The baby boomers began streaming into the first grade by the mid-1940's and became a flood by 1950. The public school system suddenly found itself overtaxed. While the number of schoolchildren rose because of wartime and postwar conditions, these same conditions made the schools even less prepared to cope with the flood. The wartime economy meant that few new schools were built between 1940 and 1945. Moreover, during the war and in the boom times that followed large numbers of teachers left their profession for better -paying jobs elsewhere in the economy.
Therefore, in the 1950's and 1960's, the baby boom hit an antiquated and inadequate school system. Consequently, the "custodial rhetoric" of the 1930's and early 1940's no longer made sense; that is, keeping youths aged sixteen and older out of the labor market by keeping them in school could no longer be a high priority for an institution unable to find space and staff to teach younger children aged five to sixteen. With the baby boom, the focus of educators and of laymen interested in education inevitably turned toward the lower grades and back to basic academic skills and discipline. The system no longer had much interest in offering nontraditional new and extra services to older youths.
【題組】13. what dose the passage mainly discuss?
(A) the teaching profession during the baby boom
(B) birth rates in United States in the 1930's and 1940's
(C) the impact of the baby boom on public education
(D) the role of the family in the 1950's and 1960's
16.【題組】16. The public schools of the 1950's and 1960's faced all of the following problems EXCEPT
(A) a declining number of students
(B) old-fashioned facilities
(C) a shortage of teachers
(D) an inadequate number of school buildings
17.【題組】17. According to the passage, why did teachers leave the teaching profession after the outbreak of the war?
(A) They needed to be retrained.
(B) They were dissatisfied with the curriculum.
(C) Other jobs provided higher salaries.
(D) Teaching positions were scarce.
19.【題組】19. The "custodial rhetoric" mentioned in line 21 refers to
(A) raising a family
(B) keeping older individuals in school
(C) running an orderly household
(D) maintaining discipline in the classroom
22.【題組】22 Which of the following best characterizes the organization of the passage?
(A) The second paragraph presents the effect of circumstances described in the first paragraph.
(B) The second paragraph provides a fictional account to illustrate a problem presented in the first paragraph.
(C) The second paragraph argues against a point made in the first paragraph.
(D) The second paragraph introduces a problem not mentioned in the first paragraph.
Nineteenth-century writers in the United States, whether they wrote novels, short stories, poems or plays were powerfully drawn to the railroad in its golden years. In fact, writers responded to the railroads as soon as the first were built in the 1830's. By the 1850's, the railroad was a major presence in the life of the nation. Writers such as Ralph Waldo Emerson and Henry David Thoreau saw the railroad both as a boon to democracy and as an object of suspicion. The railroad could be and was a despoiler of nature furthermore, in its manifestation of speed and noise, it might be a despoiler of human nature as well. By the 1850's and 1860's, there was a great distrust among writer and intellectuals of the rapid industrialization of which the railroad was a leading force. Deeply philosophical historians such as Henry Adams lamented the role that the new frenzy for business was playing in eroding traditional values. A distrust of industry and business continued among writers throughout the rest of the nineteenth century and into the twentieth.
For the most part, the literature in which the railroad plays an important role belongs to popular culture rather than to the realm of serious art. One thinks of melodramas, boy's books, thrillers, romances and the like rather than novels of the first rank. In the railroads' prime years, between 1890 and 1920, there were a few individuals in the United States, most of them with solid railroading experience behind them, who made a profession of writing about railroading - works offering the ambience of stations yards and locomotive cabs. These writers who can genuinely be said to have created a genre, the "railroad novel" are now mostly forgotten, their names having faded from memory. But anyone who takes the time to consult their fertile writings will still find a treasure trove of information about the place of the railroad in the life of the United States.
【題組】23. With which of the following topics is the passage mainly concerned?
(A) The role of the railroad in the economy of the United States
(B) Major nineteenth - century writers
(C) The conflict between expanding industry and preserving nature
(D) The railroad as a subject for literature.
25.【題組】25. In the first paragraph, the author implies that writers reactions to the development of railroads were
(A) highly enthusiastic
(B) both positive and negative
30.【題組】30. The author mentions all of the following as being true about the literature of railroads EXCEPT that
(A) many of its writers had experience working on railroads
(B) many of the books were set in railroad stations and yards
(C) the books were well known during the railroads' prime years
(D) quite a few of the books are still popular today
32.【題組】32. What is the author's attitude toward the "railroad novels" and other books about railroads written between 1890 and 1920?
(A) They have as much literary importance as the books written by Emerson. Thoreau and Adams.
(B) They are good examples of the effects industry and business had on the literature of the United States.
(C) They contributed to the weakening of traditional values.
(D) They are worth reading as sources of knowledge about the impact of railroads on life in the United States
By the 1820's in the United States, when steamboats were common on western waters, these boats were mostly powered by engines built in the West (Pittsburgh, Cincinnati or Louisville), and of a distinctive western design specially suited to western needs. The first steam engines in practical use in England and the United States were of low-pressure design. This was the type first developed by James Watt, then manufactured by the firm of Boulton and Watt, and long the standard industrial engine. Steam was accumulated in a large, double-acting vertical cylinder, but the steam reached only a few pounds of pressure per square inch. It was low-pressure engines of this type that were first introduced into the United States by Robert Fulton. He imported such a Boulton and Watt engine from England to run the Clemont. But this type of engine was expensive and complicated, requiring many precision-fitted moving parts.
The engine that became standard on western steamboats was of a different and novel design. It was the work primarily of an unsung hero of American industrial progress Oliver Evans (1755-1819). The self-educated son of a Delaware farmer, Evans early became obsessed by the possibilities of mechanized production and steam power. As early as 1802 he was using a stationary steam engine of high-pressure design in his mill. Engines of this type were not unknown, but before Evans they were generally considered impractical and dangerous.
Within a decade the high-pressure engine, the new type had become standard on western waters. Critics ignorant of western conditions often attacked it as wasteful and dangerous. But people who really knew the Ohio, the Missouri and the Mississippi insisted with good reasons, that it was the only engine for them. In shallow western rivers the weight of vessel and engine was important, a heavy engine added to the problem of navigation. The high-pressure engine was far lighter in proportion to horsepower, and with less than half as many moving parts was much easier and cheaper to repair. The main advantages of low-pressure engines were safe operation and economy of fuel consumption, neither of which meant much in the West.
【題組】33. What is the passage mainly about?
(A) Steamboat engines in the western United States
(B) River travel in the western United States
(C) A famous United States inventor
(D) The world's first practical steamboat
37.【題組】37. What opinion of Evans is suggested by the use of the term "unsung hero" in line 14?
(A) More people should recognize the importance of his work.
(B) More of his inventions should be used today.
(C) He should be credited with inventing the steam engine.
(D) More should be learned about his early life.
38.【題組】38. What does the author imply about Evans?
(A) He went to England to learn about steam power.
(B) He worked for Fulton.
(C) He traveled extensively in the West.
(D) He taught himself about steam engines.
41.【題組】41.What does the author imply about the western rivers?
(A) It was difficult to find fuel near them.
(B) They flooded frequently.
(C) They were difficult to navigate
(D) They were rarely used for transportation
44.【題組】44 . Which of the following points was made by the critics of high-pressure engines?
(A) They are expensive to import
(B) They are not powerful enough for western waters.
(C) They are dangerous.
(D) They weigh too much.
Volcanic fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes typically destroy ice fields as they did in 1980 when 70 percent of Mount Saint Helens ice cover was demolished. During long dormant intervals, glaciers gain the upper hand cutting deeply into volcanic cones and eventually reducing them to rubble. Only rarely do these competing forces of heat and cold operate in perfect balance to create a phenomenon such as the steam caves at Mount Rainier National Park.
Located inside Rainier's two ice-filled summit craters, these caves form a labyrinth of tunnels and vaulted chambers about one and one -half miles in total length. Their creation depends on an unusual combination of factors that nature almost never brings together in one place. The cave-making recipe calls for a steady emission of volcanic gas and heat, a heavy annual snowfall at an elevation high enough to keep it from melting during the summer, and a bowl-shaped crater to hold the snow.
Snow accumulating yearly in Rainier's summit craters is compacted and compressed into a dense form of ice called firm, a substance midway between ordinary ice and the denser crystalline ice that makes up glaciers. Heat rising from numerous openings (called fumaroles) along the inner crater walls melts out chambers between the rocky walls and the overlying ice pack. Circulating currents of warm air then melt additional openings in the firm ice, eventually connecting the individual chambers and, in the large of Rainier's two craters, forming a continuous passageway that extends two-thirds of the way around the crater's interior.
To maintain the cave system, the elements of fire under ice must remain in equilibrium enough snow must fill the crater each year to replace that melted from below. If too much volcanic heat is discharged, the crater's ice pack will melt away entirely and the caves will vanish along with the snows of yesteryear. If too little heat is produced, the ice, replenished annually by winter snowstorms will expand, pushing against the enclosing crater walls and smothering the present caverns in solid firm ice.
【題組】45.With what topic is the passage primarily concerned?
(A) The importance of snowfall for Mount Rainier
(B) The steam caves of Mount Rainer
(C) How ice covers are destroyed
(D) The eruption of Mount Saint Helens in 1980