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　　Naturalists and casual observers alike have been struck by the special relationship between

　　squirrels and acorns (the seeds of oak trees). Ecologists, though, cannot observe these energetic

　　mammals scurrying up and down oak trees and eating and burying acorns without wondering

　　about their complex relationship with trees. Are squirrels dispersers and planters of oak forests or

　　pesky seed 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 seeds are abundant, these 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 seed 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 seeds in tree cavities and

　　underground burrows. Only

　　squirrels — whose behavior of caching (hiding) acorns below the leaf litter — often promote

　　successful germination of acorns, and perhaps blue jays, important long-distance dispersers, seem

　　to help oaks spread and reproduce.

　　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 research is not conclusive at this point, one thing that is certain is that squirrels do

　　hide some of the uneaten portions, and these acorn halves, many of which contain the seeds, may

　　later germinate.

　　托福阅读题目：

　　1. What does the passage mainly discuss?

　　(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 seeds

　　(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?

　　(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" in line 11 is closest in meaning to

　　(A) commented

　　(B) judged

　　(C) observed

　　(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 seed dispersal of oaks

　　(C) to argue in favor of additional studies concerning the destructive force of squirrels

　　(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

　　because

　　(A) they store their acorns where they cannot germinate

　　(B) they consume most of their stored acorns

　　(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 phrase "pry off" in line 21 is closest in meaning to

　　(A) swallow

　　(B) remove

　　(C) squeeze

　　(D) locate

　　9. The word "littered" in line 22 is closest 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 seeds

　　(C) Why squirrels eat only a portion of each acorn they retrieve

　　(D) Why squirrels prefer acorns from a particular species of oak trees

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