17. A new sllencing device for domestic appliances operates by producing sound waves that cancel out the sound waves produced by the appliance. The device unlike conventional silencers actively eliminates the noise the appliance makes and for that reason vacuum cleaners designed to incorporate the new device will operate with much lower electricity consumption than conventional vacuum cleaners
Which one of the following if true most helps to explain why the new silencing device will make lower electricity consumption possible
(A) Designers of vacuum cleaner motors typically nave to compromise the motors' efficiency in order to reduce noise production
(B) The device runson electricity drawn from the appliance's main power supply
(C) Conventional vacuum clcaners often use spinning brushes to loosen dirt in addition to using suction to remove dirt
(D) Governmental standards for such domestic appliances as vacuum cleaners allow higher electricity consumption when vacuum cleaners are quieter
(E) The need to incorporate silencers in conventional vacuum cleaners makes them neavier and less mobile than they might otherwise be
18. Because dinosaurs were reptiles, scientists once assumed that, like all reptilles alive today, dinosaurs were cold-blooded. The recent discovery of dinosaur fossils in the northern arctic however has led a number of researchers to conclude that at least some dinosaurs might have been warm-blooded. These researchers point out that only warm-blooded animals could have withstood the frigid temperatures that are characteristic of arctic winters, whereas cold-blooded animals would have frozen to death in the extreme cold
Which one of the following if true weakens the researchers' argument?
(A) Today's reptiles are generally confined to regions of temperate or even tropical climates
(B) The fossils show the arcuc dinosaurs to have been substantially smaller than other known species of dinosaurs.
(C) The arctic dinosaur fossils were found alongside fossils of plants known for their abiliry to witnstand extremely cold temperatures.
(D) The number of fossils found together inchcates herds of dinosaurs so large that they would need to migrate to find a continual food supply
(E) Experts on prehistoric climatic conditions believe that winter temperatures in the prehistoric northern arctic were not significantly different from what they are today.
Question 19-20
Maria: Calling any state totalitarian is misleading it implies total state control of all aspects of life. The real world contains no political entity exercising literally total control over even one such aspect. This is because any system of control is inefficient, and, therefore, its degree of control is partial.
James: A one-party state that has tried to exercise control over most aspects of a society and that has broadly speaking managed to do so is totalitarian. Such a system's practical inefficiencies do not limit the aptness of the term, which does not describe a state's actual degree of control as much as it describes the nature of a state's ambitions.
19. Which one of the following most accurately expresses Marla's man conclusion?
(A) No state can be called totalitarian without inviting a mistaken belief
(B) To be totalitarian a state must totally control society
(C) The degree of control exercised by a state is necessarily partial
(D) No existing state currently has even one aspect of society under total control
(E) Systems of control are inevitably inefficient
20. James responds to Maria's argument by
(A) pointing out a logical inconsistency between two statements she makes in support of her argument
(B) offering an alternative explanation for political conditions she mentions
(C) rejecting some of the evidence she presents without challenging what she infers from it
(D) disputing the conditions under which a key term of her argument can be appropriately applied
(E) demonstrating that her own premises lead to a conclusion different from hers
21. The similarity between ichthyosaurs and fish is an example of convergence, a process by which different classes of organisms adapt to the same environment by independently developing one or more similar external body features. I chthyosaurs were marine reptiles and thus do not belong to the same class of organisms as fish. However, ichthyosaurs adapted to their marine environment by converging on external body features similar to those of fish. Most strikingly, ichthydsaurs, like fish, had fins.
If the statements above are true, which one of the following is an inference that can be properly drawn on the basis of them?
(A) The members of a single class of organisms that inhabit the same environment must be identical in all their external body features
(B) The members of a single class of organisms must exhibit one or more similar external body features that differentiate that class from all other classes of organisms.
(C) It is only as a result of adaptation to similar environments that one class of organisms develops external body features similar to those of another class of organisms.
(D) An organism does not necessarily belong to a class simply because the organism has one or more external body features similar to those of members of that class
(E) Whenever two classes of organisms share the same environment members of one class will differ from members of the other class in several external body features.
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