美国GRE出国考试模拟试题6
2011-09-29 11:19:00   来源：作文地带整理    双击单词自动翻译

　　美国GRE出国考试模拟试题6

　　One explanation for the tendency of animals to be

　　more vigilant in smaller groups than in larger ones

　　assumes that the vigilant behavior—looking up, for

　　example—is aimed at predators. If individuals on the(5) edge of a group are more vigilant because they are at 美国GREater risk of being captured, then individuals on aver-age would have to be more vigilant in smaller groups, because the animals on the periphery of a group form a 美国GREater proportion of the whole group as the size of the

　　(10)group diminishes.

　　However, a different explanation is necessary in cases where the vigilant behavior is not directed at predators. J. Krebs has discovered that 美国GREat blue herons look up more often when in smaller flocks than when in larger

　　(15)ones, solely as a consequence of poor feeding conditions. Krebs hypothesizes that the herons in smaller flocks are watching for herons that they might follow to better feeding pools, which usually attract larger numbers ofthe birds.

　　17.It can be inferred from the passage that in species in which vigilant behavior is directed at predators, the tendency of the animals to be more vigilant in smaller groups than in larger ones would most likely be minimized if which of the following were true?

　　(A) The vigilance of animals on the periphery of a group always exceeded that of animals located in its interior, even when predators were not in the area.

　　(B) The risk of capture for individuals in a group was the same, whether they were located in the interior of the group or on its periphery.

　　(C) Animals on the periphery of a group tended to be less capable of defending themselves from attack by predators than animals located in the interior of the group.

　　(D) Animals on the periphery of a group tended to bear marks that were more distinctive to predators than animals located in the interior of the group.

　　(E) Animals on the periphery of a group tended to have shorter life spans than animals located in the interior of the group.

　　18.Whch of the following best describes the relationship of the second paragraph to the first?

　　(A)The second paragraph relies on different evidence in drawing a conclusion similar to that expressed in the first paragraph.

　　(B)The second paragraph provides further elaboration on why an assertion made at the end of the first paragraph proves to be true in most cases.

　　(C)The second paragraph provides additional information in support of a hypothesis stated in the first paragraph.

　　(D)The second paragraph provides an example of a case in which the assumption described in the first paragraph is unwarranted.

　　(E) The second paragraph describes a phenomenon that has the same cause as the phenomenon described in the first paragraph.

　　19.It can be inferred from the passage that the author of the passage would be most likely to a美国GREe with which of the following assertions about vigilant behavior?