托福阅读专项练习题及答案
Naturalists and casual obrvers alike have been struck by the special relationship between squirrels and acorns (the eds of oak trees). Ecologists, though, cannot obrve the energetic mammals scurrying up and down oak trees and eating and burying acorns without wondering about their complex relationship with trees. Are squirrels disperrs and planters of oak forests or pesky ed predators? The answer is not simple. Squirrels may devour many acorns, but by storing and failing to recover up to 74 percent of them as they do when eds are abundant, the arboreal rodents can also aid regeneration and dispersal of the oaks.
Their destructive powers are well documented. According to one report, squirrels destroyed tens of thousands of fallen acorns from an oak stand on the University of Indiana campus. A professor there estimated that each of the large white oaks had produced between two and eight thousand acorns, but within weeks of ed maturity, hardly an intact acorn could be found among the fallen leaves.
Deer, turkey, wild pigs, and bears also feed heavily on acorns, but do not store them, and are therefore of no benefit to the trees. Flying squirrels, chipmunks, and mice are also unlikely to promote tree dispersal, as they often store eds in tree cavities and underground burrows. Only squirrels — who behavior of caching (hiding) acorns below the leaf litter — often promote successful germination of acorns, and perhaps blue jays, important long-distance disperrs, em to help oaks spread and reproduce.
analy是什么意思Among squirrels, though, there is a particularly puzzling behavior pattern. Squirrels pry off the caps of acorns, bite through the shells to get at the nutritious inner kernels, and then discard them half-eaten. The ground under towering oaks is often littered with thousands of half-eaten acorns, each one only bitten from the top. Why would any animal waste so much time and energy and risk exposure to such predators as red-tail hawks only to leave a large part of each acorn uneaten? While rearch is not conclusive at this point, one thing that is certain is that squirrels do hide some of the uneaten portions, and the acorn halves, many of which contain the eds, may later germinate.
1. What does the passage mainly discuss?
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(A) The ecology of oak trees
(B) Factors that determine the feeding habits of Squirrels
(C) Various species of animals that promote the dispersal of tree eds
(D) The relationship between squirrels and oak trees
2. The word "they" in line 7 refers to
(A) oak forests
(B) acorns
(C) squirrels
(D) predators
3. According to the passage , what do squirrels do when large quantities of acorns are available?
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(A) They do not store acorns.
(B) They eat more than 74 percent of available acorns.
(C) They do not retrieve all the acorns that they have stored.
(D) They hide acorns in tree cavities.
4. The word "estimated评价，估计，估价，判断" in line 11 is clost in meaning to
(A) commented
(B) judged
(C) obrved
(D) discovered
5. Why does the author mention "the University of Indiana campus" in line 10 -11?
(A) to provide evidence that intact acorns are hard to find under oak trees
(B) to indicate a place where squirrels can aid ed dispersal of oaks
高光笔(C) to argue in favor of additional studies concerning the destructive force of squirrelsahoy
(D) to support the claim that squirrels can do great damage to oak stands
6. It can be inferred from paragraph 3 that chipmunks do not aid in the dispersal of oak trees becau
(A) they store their acorns where they cannot germinate
(B) they consume most of their stored acorns报关员培训班
(C) their stored acorns are located and consumed by other species
(D) they cannot travel the long distance required for dispersal
7. According to the passage , which of the following do squirrels and blue jays have in common?
(A) They travel long distances to obtain acorns.
(B) They promote the reproduction of oak trees.
(C) They bury acorns under fallen leaves.
(D) They store large quantities of acorns.
8. The phra "pry 撬off" in line 21 is clost in meaning to
(A) swallow 吞
(B) remove低调做人高调做事>考研复试技巧
(C) squeeze
language exchange(D) locate
9. The word "littered" in line 22 is clost in meaning to
(A) covered
(B) displayed
(C) fertilized
(D) planted
10. According to the passage , scientists cannot explain which of the following aspects of squirrel behavior?
(A) Where squirrels store their acorn caches
(B) Why squirrels prefer acorns over other eds
(C) Why squirrels eat only a portion of each acorn they retrieve
i pad(D) Why squirrels prefer acorns from a particular species of oak trees
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