Official 38 Passage 2
答题结果:0/14
答题时间:0''
Question 14 of 14

Directions: 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 passage or are minor ideas in the passage. This question is worth 2 points.


In 1943 raccoon populations in North America began to expand rapidly, probably becoming fifteen to twenty times larger by the late 1980s.
Answer Choices:

A.

Raccoon populations have grown in part because of expansion into new habitats created by the growth of urban and especially suburban areas and perhaps by the spread of agriculture in some regions.

B.

Raccoons are native species only from southern Canada through Central America, but in the twentieth century they successfully migrated to most other regions of the Western Hemisphere.

C.

Raccoons have been deliberately introduced throughout the United States and in other parts of the world, and transplanted individuals are often rapidly able to exploit new environments.

D.

Raccoons became established in Canada when coyotes expanded into their habitats in the United States.

E.

It is unlikely that raccoon populations will grow in the future at the rate they have since 1943 because raccoons have now colonized most of the habitats suitable for them.

F.

The elimination of wolves from much of the United States was probably essential to raccoons’ expansion and numerical increase, and the control of coyotes might also have contributed.

我的答案:

正确答案:ACF

译文

The Racoon's Success

[#paragraph1]Raccoons have a vast transcontinental distribution, occurring throughout most of North America and Central America. [#insert1] They are found from southern Canada all the way to Panama, as well as on islands near coastal areas. [#insert2] They occur in each of the 49 states of the continental United States. [#insert3] Although raccoons are native only to the Western Hemisphere, they have been successfully transplanted to other parts of the globe. [#insert4]
 

[#paragraph2]Following a decline to a relatively low population level in the 1930s, raccoons began to prosper following their 1943 breeding season. A rapid population surge continued throughout the 1940s, and high numbers have been sustained ever since. By the late 1980s, the number of raccoons in North America was estimated to be at least 15 to 20 times the number that existed during the 1930s. [#highlight2]By now, their numbers have undoubtedly grown even more, as they have continued to expand into new habitats where they were once either rare or absent, such as sandy prairies, deserts, coastal marshes, and mountains.[/highlight2] Their spread throughout the Rocky Mountain West is indicative of the fast pace at which they can exploit new environments. Despite significant numbers being harvested and having suffered occasional declines, typically because of disease, the raccoon has [#highlight3]consistently[/highlight3] maintained high population levels.
 

[#paragraph3]Several factors explain the raccoon’s dramatic increase in abundance and distribution. First, their success has been partially attributed to the growth of cities, as they often thrive in suburban and even urban settings. Furthermore, they have been deliberately introduced throughout the continent. Within the United States, they are commonly taken from one area to another, both legally and illegally, to restock hunting areas and, [#highlight7]presumably[/highlight7], because people simply want them to be part of their local fauna. Their appearance and subsequent flourishing in Utah’s Great Salt Lake valley within the last 40 years appears to be from such an introduction. As an example of the ease with which transplanted individuals can succeed, raccoons from Indiana (midwestern United States) have reportedly been able to flourish on islands off the coast of Alaska.
 

[#paragraph4]The raccoon’s expansion in various areas may also be due to the spread of agriculture. Raccoons have been able to exploit crops, especially corn but also cereal grains, which have become dependable food sources for them. The expansion of agriculture, however, does not necessarily lead to rapid increases in their abundance. Farming in Kansas and eastern Colorado (central and western United States) proceeded rapidly in the 1870s and 1880s, but this was about 50 years before raccoons started to spread out from their major habitat, the wooded river bottomlands. They have also expanded into many areas lacking any agriculture other than grazing and into places without forests or permanent streams.
 

[#paragraph5]Prior to Europeans settling and farming the Great Plains region, a vast grassland region in North America extending from central Canada south through the west central United States into Texas, raccoons probably were just found along its rivers and streams and in the wooded areas of its southeastern section. With the possible exception of the southern part of the province of Manitoba, their absence was notable throughout Canada. They first became more widely distributed in the southern part of Manitoba, and by the 1940s were abundant throughout its southeastern portion. In the 1950s their population swelled in Canada. The control of coyotes in the prairie region in the 1950s may have been a factor in raccoon expansion. If their numbers are sufficient, coyotes might be able to suppress raccoon populations (though little direct evidence supports this notion). By the 1960s the raccoon had become a major predator of the canvasback ducks nesting in southwestern Manitoba.
 

[#paragraph6]The extermination of the wolf from most of the contiguous United States may have been a [#highlight11]critical[/highlight11] factor in the raccoon’s expansion and numerical increase. In the eighteenth century, when the wolf’s range included almost all of North America, raccoons apparently were abundant only in the deciduous forests of the East, Gulf Coast, and Great Lakes regions, though they also extended into the wooded bottomlands of the Midwest’s major rivers. In such areas, their arboreal habits and the presence of hollow den trees should have offered some protection from wolves and other large predators. Even though raccoons may not have been a significant part of their diet, wolves surely would have tried to prey on those exposed in relatively treeless areas.