历年GRE真题试题之六(B)

9. In recent years, there has been a dramatic decline in the population of the shrike, a predatory bird that inhabits flat land, such as farms and pastures. Some ornithologists hypothesize that this decline is due to the introduction of new, more effective pesticides to control the insect species on which shrikes prey.The answer to which of the following questions is NOT relevant to evaluating the ornithologists’ hypothesis?
(A) Was there a decline in the shrike population before the new pesticides were first used?
(B) Have shrike populations declined significantly in those habitats where the new pesticides have not been used?
(C) Have the new pesticides more significantly reduced the population of insect species on which shrikes prey than did the pesticides previously used?
(D) Are insects that have consumed the new pesti-cides more toxic to the shrikes that eat those insects than were insects that consumed the less effective pesticides?
(E) Are the new pesticides considered by most people to be less harmful to the environment than the old pesticides were considered to be?
10. Census data for Prenland show that unmarried Prenlandic men in their thirties outnumber unmarried Prenlandic women in that age group by about ten to One. Most of these men do wish to marry. Clearly, however, unless many of them marry women who are not Prenlandic, all but a minority will remain unmarried.
The argument makes which of the following assump-tions?
(A) Emigration from Preland is more common among women than among men.
(B) A greater proportion of Prelandic women in their thirties than of Prenlandic men of the same age would prefer to remain unmarried.
(C) It is unlikely that many of these unmarried Prenlandic men will marry women more than a few years older than themselves.
(D) Prenland has a high rate of divorce.
(E) Most of the unmarried Prenlandic men are unwilling to marry women who are not Prenlandic.
11.Certain extremely harmful bacteria found only in sewage are difficult to detect directly. Testing for E. coli, an easily detected and less harmful type of bacteria, in ocean water would be a reliable way of determining whether or not these more harmful bac-teria are present, since ocean water contains E. Coli only if the water is contaminated with sewage that contains the harmful bacteria. Which  of the following, if true, most seriously weakens the argument?
(A) There are many different strains of the E. coli bacteria, and only some of these strains are harmful.
(B) Some types of bacteria found in sewage are neither disease-causing nor difficult to detect directly.
(C) Some of the types of bacteria found in sewage along with E. coli are not harmful to people unless the bacteria are ingested in large quantities.
(D) E. coli dies out much more quickly than some of the more harmful bacteria found in sewage and then can no longer be easily detected.
(E) Some of the types of bacteria found in sewage along with E. coli reproduce at a slower rate than E. coli.
Questions 12-17
A bank has exactly four cashier windows, arranged in a row and numbered consecutively 1through 4 from one end of the row to the other. The bank has exactly six cashiers: two supervisors (Joan and Karim); and four trainees (Lorraine, Mark, Nora, and patrick). Throughout a particular peak-hour period, the stationing of cashiers at windows is restricted as follows:
There must be exactly one cashier at each window.The cashier at window 2 must be a supervisor.
Lorraine must be at a window but cannot be at window 3. If Mark is at one of the windows, Joan must be at a window immediately adjacent to it. The cashiers at the windows must include either Nora or Patrick, but they cannot include both Nora and Patrick.
12.Which of the following lists the cashiers who can be stationed at windows 1 through 4 during this period?1 2 3 4
(A) Joan Karim Mark Lorraine
(B) Joan Karim Nora Lorraine
(C) Karim Nora Joan Lorraine
(D) Mark Joan Lorraine Patrick
(E) Patrick Joan Nora Lorraine
13.Which of the following must be true about the stationing of the cashiers during this period?
(A) Joan is at window 1 orat window 2.
(B) Karim is at window 2 or at window 4.
(C) Lorraine is at window 1 or window 4.
(D) Nora is at window 1 or at window 3.
(E) Patrick is at window 3 or at window 4.
14.sarily in that order, are stationed at immediately adjacent windows, which of the following must be stationed at window 4 during this period?
(A) Joan
(B) Karim
(C) Lorraine
(D) Mark
(E) Patrick
15.If during this period Lorraine and Mark, not neces-sarily in that order, are stationed at immediately adjacent windows, which of the following can be stationed at window 1 during this period?
(A) Joan
(B) Karim
(C) Lorraine
(D) Mark
(E) Nora
16.If during this period Lorrained and Nora, not neces-sarily in that order, are stationed at immediately adjacent windows, which of the following must be true during this period?
(A) Joan is stationed at window 1.
(B) Joan is stationed at window 2.
(C) Karim is stationed at window 2
(D) Nora is stationed at windows 3.
(E) Patrick is stationed at window 1.
17.If during this period Mark is stationed at a window,which of the following CANNOT be stationed at a window during this period?
(A) Joan
(B) Karim
(C) Lorraine
(D) Nora
(E) Patrick
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